Display the bounds of each text node in the text_debug ui example (#…

…15622)

# Objective

Add a background colour to each text node in the `text_debug` example to
visualize their bounds.

## Showcase

<img width="961" alt="deb"
src="https://github.com/user-attachments/assets/deec3e15-b0f0-411f-9af1-597587ac2a83">

In the bottom right you can see the empty space at the bottom of the
text node, making it much more obvious that there is a bug causing the
size of the bounds to be calculated incorrectly.

examples/ui/text_debug.rs

@@ -31,7 +31,9 @@ struct TextChanges;
 
 fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  let font = asset_server.load("fonts/FiraSans-Bold.ttf");
+ let background_color = MAROON.into();
  commands.spawn(Camera2d);
+
  let root_uinode = commands
  .spawn(NodeBundle {
  style: Style {
@@ -64,6 +66,7 @@ fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  ..default()
  },
  )
+ .with_background_color(background_color)
  );
  builder.spawn(TextBundle::from_section(
  "This text is right-justified. The `JustifyText` component controls the horizontal alignment of the lines of multi-line text relative to each other, and does not affect the text node's position in the UI layout.", TextStyle {
@@ -77,6 +80,7 @@ fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  max_width: Val::Px(300.),
  ..default()
  })
+ .with_background_color(background_color)
  );
  builder.spawn(
  TextBundle::from_section(
@@ -91,6 +95,7 @@ fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  max_width: Val::Px(300.),
  ..default()
  })
+ .with_background_color(background_color)
  );
  }).id();
 
@@ -119,6 +124,7 @@ fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  max_width: Val::Px(400.),
  ..default()
  })
+ .with_background_color(background_color)
  );
 
  builder.spawn(
@@ -134,7 +140,8 @@ fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  .with_style(Style {
  max_width: Val::Px(300.),
  ..default()
- }),
+ })
+ .with_background_color(background_color)
  );
 
  builder.spawn(
@@ -150,7 +157,8 @@ fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  .with_style(Style {
  max_width: Val::Px(300.),
  ..default()
- }),
+ })
+ .with_background_color(background_color)
  );
 
  builder.spawn((
@@ -221,12 +229,11 @@ fn infotext_system(mut commands: Commands, asset_server: Res<AssetServer>) {
  color: BLUE.into(),
  },
  ),
- ]),
+ ]).with_background_color(background_color),
  TextChanges,
  ));
  })
  .id();
-
  commands
  .entity(root_uinode)
  .add_children(&[left_column, right_column]);