Add sprite flipping to testbed_2d's sprite scene (#18537)

# Objective

Add sprite flipping to `testbed_2d`'s sprite scene

## Solution

Draw the sprite flipped in each axis and both axes.

Changed the sprite to the rectangular bevy banner with text and made the
images different colors.

## Testing
```
cargo run --example testbed_2d
```


![image](https://github.com/user-attachments/assets/dcfe687b-2f40-4417-bb20-6c892b425228)

---------

Co-authored-by: François Mockers <mockersf@gmail.com>

examples/testbed/2d.rs

@@ -258,14 +258,30 @@ mod text {
 }
 
 mod sprite {
+    use bevy::color::palettes::css::{BLUE, LIME, RED};
     use bevy::prelude::*;
+    use bevy::sprite::Anchor;
 
     pub fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         commands.spawn((Camera2d, StateScoped(super::Scene::Sprite)));
-        commands.spawn((
-            Sprite::from_image(asset_server.load("branding/bevy_bird_dark.png")),
-            StateScoped(super::Scene::Sprite),
-        ));
+        for (anchor, flip_x, flip_y, color) in [
+            (Anchor::BOTTOM_LEFT, false, false, Color::WHITE),
+            (Anchor::BOTTOM_RIGHT, true, false, RED.into()),
+            (Anchor::TOP_LEFT, false, true, LIME.into()),
+            (Anchor::TOP_RIGHT, true, true, BLUE.into()),
+        ] {
+            commands.spawn((
+                Sprite {
+                    image: asset_server.load("branding/bevy_logo_dark.png"),
+                    anchor,
+                    flip_x,
+                    flip_y,
+                    color,
+                    ..default()
+                },
+                StateScoped(super::Scene::Sprite),
+            ));
+        }
     }
 }