Update container (and a couple other) icons (#4814)

### What

#4663 introduced a bunch of new icons, but the container icons were a
tad too busy. This PR introduce the new version from @martenbjork, along
with a couple other minor icon tweaks.

New icons:

<img width="356" alt="image"
src="https://github.com/rerun-io/rerun/assets/49431240/0fd5def6-3bce-47e0-9472-81211ffd9697">

In the UI:

<img width="155" alt="image"
src="https://github.com/rerun-io/rerun/assets/49431240/cf0c323d-fcc0-4655-960f-769ce3a80647">


### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/4814/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/4814/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/4814/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG

- [PR Build Summary](https://build.rerun.io/pr/4814)
- [Docs
preview](https://rerun.io/preview/029bfa78e1a698757f9b6483e899838a0038724a/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/029bfa78e1a698757f9b6483e899838a0038724a/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

crates/re_data_ui/src/item_ui.rs

@@ -222,7 +222,7 @@ pub fn data_blueprint_group_button_to(
         .re_ui
         .selectable_label_with_icon(
             ui,
-            &re_ui::icons::CONTAINER,
+            &re_ui::icons::GROUP,
             text,
             ctx.selection().contains_item(&item),
         )

crates/re_ui/src/icons.rs

@@ -133,7 +133,7 @@ pub const SPACE_VIEW_UNKNOWN: Icon = Icon::new(
     include_bytes!("../data/icons/spaceview_unknown.png"),
 );
 
-pub const CONTAINER: Icon = Icon::new("container", include_bytes!("../data/icons/container.png"));
+pub const GROUP: Icon = Icon::new("group", include_bytes!("../data/icons/group.png"));
 
 pub const STORE: Icon = Icon::new("store", include_bytes!("../data/icons/store.png"));
 

crates/re_viewer/src/ui/selection_panel.rs

@@ -392,7 +392,7 @@ fn what_is_selected_ui(
                     ctx.re_ui,
                     ui,
                     &entity_path.to_string(),
-                    Some(&re_ui::icons::CONTAINER),
+                    Some(&re_ui::icons::GROUP),
                     &format!(
                         "Group {:?} as shown in Space View {:?}",
                         entity_path, space_view.display_name

crates/re_viewport/src/viewport.rs

@@ -762,7 +762,7 @@ impl TabWidget {
         // tab icon
         let icon_size = ReUi::small_icon_size();
         let icon_width_plus_padding = icon_size.x + ReUi::text_to_icon_padding();
-        let icon = space_view.map_or(&re_ui::icons::CONTAINER, |space_view| {
+        let icon = space_view.map_or(&re_ui::icons::SPACE_VIEW_GENERIC, |space_view| {
             space_view
                 .class(tab_viewer.ctx.space_view_class_registry)
                 .icon()

crates/re_viewport/src/viewport_blueprint_ui.rs

@@ -345,7 +345,7 @@ impl Viewport<'_, '_> {
                     .selected(is_selected)
                     .subdued(!properties.visible || !group_is_visible)
                     .force_hovered(is_item_hovered)
-                    .with_icon(&re_ui::icons::CONTAINER)
+                    .with_icon(&re_ui::icons::GROUP)
                     .with_buttons(|re_ui, ui| {
                         let vis_response = visibility_button_ui(
                             re_ui,