…rror for insert_reflected

Small fix for a forgotten documentation comment.

# Objective

Fix bevyengine#1018 (Textures on the
`Plane` shape appear flipped).

This bug have been around for a very long time apparently, I tested it
was still there (see test code bellow) and sure enough, this image:


![test](https://github.com/bevyengine/bevy/assets/134181069/4cda7cf8-57d9-4677-91f5-02240d1e79b1)

... is flipped vertically when used as a texture on a plane (in main,
0.10.1 and 0.9):

![image](https://github.com/bevyengine/bevy/assets/134181069/0db4f52a-51af-4041-9c45-7bfe1f08b0cc)

I'm pretty confused because this bug is so easy to fix, it has been
around for so long, it is easy to encounter, and PRs touching this code
still didn't fix it: bevyengine#7546 To the
point where I'm wondering if it's actually intended. If it is, please
explain why and this PR can be changed to "mention that in the doc".

## Solution

Fix the UV mapping on the Plane shape

Here is how it looks after the PR

![image](https://github.com/bevyengine/bevy/assets/134181069/e07ce641-3de8-4da3-a4f3-95a6054c86d7)

## Test code

```rust
use bevy::{
    prelude::*,
};

fn main () {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_startup_system(setup)
        .run();
}

fn setup(
    mut commands: Commands,
    assets: ResMut<AssetServer>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    commands.spawn(Camera3dBundle {
        transform: Transform::from_xyz(0., 3., 0.).looking_at(Vec3::ZERO, Vec3::NEG_Z),
        ..default()
    });

    let mesh = meshes.add(Mesh::from(shape::Plane::default()));
    let texture_image = assets.load("test.png");
    let material = materials.add(StandardMaterial { 
        base_color_texture: Some(texture_image),
        ..default()
    });
    commands.spawn(PbrBundle {
        mesh,
        material,
        ..default()
    });
}
```

## Changelog

Fix textures on `Plane` shapes being flipped vertically.

## Migration Guide

Flip the textures you use on `Plane` shapes.

![image](https://github.com/bevyengine/bevy/assets/47158642/dbb62645-f639-4f2b-b84b-26fd915c186d)

# Objective

- Add Screen space ambient occlusion (SSAO). SSAO approximates
small-scale, local occlusion of _indirect_ diffuse light between
objects. SSAO does not apply to direct lighting, such as point or
directional lights.
- This darkens creases, e.g. on staircases, and gives nice contact
shadows where objects meet, giving entities a more "grounded" feel.
- Closes bevyengine#3632.

## Solution

- Implement the GTAO algorithm.
-
https://www.activision.com/cdn/research/Practical_Real_Time_Strategies_for_Accurate_Indirect_Occlusion_NEW%20VERSION_COLOR.pdf
-
https://blog.selfshadow.com/publications/s2016-shading-course/activision/s2016_pbs_activision_occlusion.pdf
- Source code heavily based on [Intel's
XeGTAO](https://github.com/GameTechDev/XeGTAO/blob/0d177ce06bfa642f64d8af4de1197ad1bcb862d4/Source/Rendering/Shaders/XeGTAO.hlsli).
- Add an SSAO bevy example.

## Algorithm Overview
* Run a depth and normal prepass
* Create downscaled mips of the depth texture (preprocess_depths pass)
* GTAO pass - for each pixel, take several random samples from the
depth+normal buffers, reconstruct world position, raytrace in screen
space to estimate occlusion. Rather then doing completely random samples
on a hemisphere, you choose random _slices_ of the hemisphere, and then
can analytically compute the full occlusion of that slice. Also compute
edges based on depth differences here.
* Spatial denoise pass - bilateral blur, using edge detection to not
blur over edges. This is the final SSAO result.
* Main pass - if SSAO exists, sample the SSAO texture, and set occlusion
to be the minimum of ssao/material occlusion. This then feeds into the
rest of the PBR shader as normal.

---

## Future Improvements
- Maybe remove the low quality preset for now (too noisy)
- WebGPU fallback (see below)
- Faster depth->world position (see reverted code)
- Bent normals 
- Try interleaved gradient noise or spatiotemporal blue noise
- Replace the spatial denoiser with a combined spatial+temporal denoiser
- Render at half resolution and use a bilateral upsample
- Better multibounce approximation
(https://drive.google.com/file/d/1SyagcEVplIm2KkRD3WQYSO9O0Iyi1hfy/view)

## Far-Future Performance Improvements
- F16 math (missing naga-wgsl support
https://github.com/gfx-rs/naga/issues/1884)
- Faster coordinate space conversion for normals
- Faster depth mipchain creation
(https://github.com/GPUOpen-Effects/FidelityFX-SPD) (wgpu/naga does not
currently support subgroup ops)
- Deinterleaved SSAO for better cache efficiency
(https://developer.nvidia.com/sites/default/files/akamai/gameworks/samples/DeinterleavedTexturing.pdf)

## Other Interesting Papers
- Visibility bitmask
(https://link.springer.com/article/10.1007/s00371-022-02703-y,
https://cdrinmatane.github.io/posts/cgspotlight-slides/)
- Screen space diffuse lighting
(https://github.com/Patapom/GodComplex/blob/master/Tests/TestHBIL/2018%20Mayaux%20-%20Horizon-Based%20Indirect%20Lighting%20(HBIL).pdf)

## Platform Support
* SSAO currently does not work on DirectX12 due to issues with wgpu and
naga:
  * gfx-rs/wgpu#3798
  * gfx-rs/naga#2353
* SSAO currently does not work on WebGPU because r16float is not a valid
storage texture format
https://gpuweb.github.io/gpuweb/wgsl/#storage-texel-formats. We can fix
this with a fallback to r32float.

---

## Changelog

- Added ScreenSpaceAmbientOcclusionSettings,
ScreenSpaceAmbientOcclusionQualityLevel, and
ScreenSpaceAmbientOcclusionBundle

---------

Co-authored-by: IceSentry <[email protected]>
Co-authored-by: IceSentry <[email protected]>
Co-authored-by: Daniel Chia <[email protected]>
Co-authored-by: Elabajaba <[email protected]>
Co-authored-by: Robert Swain <[email protected]>
Co-authored-by: robtfm <[email protected]>
Co-authored-by: Brandon Dyer <[email protected]>
Co-authored-by: Edgar Geier <[email protected]>
Co-authored-by: Nicola Papale <[email protected]>
Co-authored-by: Carter Anderson <[email protected]>

- Cleanup the `reflect.rs` file in `bevy_ecs`, it's very large and can
get difficult to navigate

- Split the file into 3 modules, re-export the types in the
`reflect/mod.rs` to keep a perfectly identical API.
- Add **internal** architecture doc explaining how `ReflectComponent`
works. Note that this doc is internal only, since `component.rs` is not
exposed publicly.

To review this change properly, you need to compare it to the previous
version of `reflect.rs`. The diff from this PR does not help at all!
What you will need to do is compare `reflect.rs` individually with each
newly created file.

Here is how I did it:

- Adding my fork as remote `git remote add nicopap
https://github.com/nicopap/bevy.git`
- Checkout out the branch `git checkout nicopap/split_ecs_reflect`
- Checkout the old `reflect.rs` by running `git checkout HEAD~1 --
crates/bevy_ecs/src/reflect.rs`
- Compare the old with the new with `git diff --no-index
crates/bevy_ecs/src/reflect.rs crates/bevy_ecs/src/reflect/component.rs`

You could also concatenate everything into a single file and compare
against it:

- `cat
crates/bevy_ecs/src/reflect/{component,resource,map_entities,mod}.rs >
new_reflect.rs`
- `git diff --no-index  crates/bevy_ecs/src/reflect.rs new_reflect.rs`

…rror for insert_reflected

- Cleanup the `reflect.rs` file in `bevy_ecs`, it's very large and can
get difficult to navigate

- Split the file into 3 modules, re-export the types in the
`reflect/mod.rs` to keep a perfectly identical API.
- Add **internal** architecture doc explaining how `ReflectComponent`
works. Note that this doc is internal only, since `component.rs` is not
exposed publicly.

To review this change properly, you need to compare it to the previous
version of `reflect.rs`. The diff from this PR does not help at all!
What you will need to do is compare `reflect.rs` individually with each
newly created file.

Here is how I did it:

- Adding my fork as remote `git remote add nicopap
https://github.com/nicopap/bevy.git`
- Checkout out the branch `git checkout nicopap/split_ecs_reflect`
- Checkout the old `reflect.rs` by running `git checkout HEAD~1 --
crates/bevy_ecs/src/reflect.rs`
- Compare the old with the new with `git diff --no-index
crates/bevy_ecs/src/reflect.rs crates/bevy_ecs/src/reflect/component.rs`

You could also concatenate everything into a single file and compare
against it:

- `cat
crates/bevy_ecs/src/reflect/{component,resource,map_entities,mod}.rs >
new_reflect.rs`
- `git diff --no-index  crates/bevy_ecs/src/reflect.rs new_reflect.rs`

…ected_to_entity_commands' into implement_insert_and_remove_reflected_to_entity_commands

# Conflicts:
#	crates/bevy_ecs/src/reflect/entity_commands.rs
#	crates/bevy_ecs/src/reflect/mod.rs