Expose pixel snapping settings add pixel-art notes

[sabslikesobs]

This small in-engine documentation change aims to make it easier to discover ways to handle pixel art aesthetics.

• I have moved 2D pixel snapping settings out of "Advanced." This now matches other pixel-art-friendly settings for GUI Snapping and Default Texture filtering.
• I've added notes to the project settings and Sprite/AnimatedSprite sources to hint users towards better understanding of why pixelated sprites may not work correctly and what to do about it. This should help users make informed decisions for their needs.

Context: Proper handling of pixel art in Godot is routinely frustrating for new users: I, like others, assumed that Godot would act on pixels, not subpixels, when I was working a pixel art game. I was confused when my interpolations would appear blurry, and when pixel textures would be distorted for no apparent reason (this was because of centering). I had naively thought that setting Linear interpolation would be the single "it's a pixel art game" toggle, but that only hid the underlying issues until later. I had no idea there was a snap-to-pixel option because it was hidden in the Advanced options--my default assumption was that a pixel art game would want no subpixels at all.

Some references for the frustrations of other users:

• Pixel distortions at texture edges with centered sprite that has odd dimensions #82696
• https://www.reddit.com/r/godot/comments/fah25e/best_way_to_achieve_pixel_perfect_rendering/
• https://shaggydev.com/2021/09/21/project-setup-for-pixel-art/

[sabslikesobs]

I fixed the mistaken GLOBAL_DEF location.

[Mickeon]

I do appreciate the effort, I really do, as I can relate to this.

But the PR's descriptions are a tad too excessive. By being so verbose and specific they are difficult to read, and they do the opposite of what they clearly try to achieve.

[sabslikesobs]

@Mickeon Thanks for your review. I've cut most of the text, as I agree that those details are not necessary for editor documentation hints, and the main issues of discoverability are still solved--a user who experiences mysterious distortion from centering or something should be able to find pixel snapping a little easier.

[sabslikesobs]

(Accepted all review suggestions)

[Mickeon]

It's good in its current state, with a few nitpicks.

I like this slight extra nudge in the documentation to ease up pixel art developers. I don't think it will completely remove any need of external help, but it is nice to have.

[sabslikesobs]

Thanks, I applied your suggestions. A few other notes in the same file also use the term "games."

[Mickeon]

Remember to squash your commits, see https://docs.godotengine.org/en/stable/contributing/workflow/pr_workflow.html#the-interactive-rebase

[sabslikesobs]

Squashed into one commit.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉