Add support for skybox transformation

[Soulghost]

Objective

• Fixes https://github.com/bevyengine/bevy/issues/14036

Solution

• Add a view space transformation for the skybox

Testing

• I have tested the newly added transform field using the skybox example.

diff --git a/examples/3d/skybox.rs b/examples/3d/skybox.rs
index beaf5b268..d16cbe988 100644
--- a/examples/3d/skybox.rs
+++ b/examples/3d/skybox.rs
@@ -81,6 +81,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         Skybox {
             image: skybox_handle.clone(),
             brightness: 1000.0,
+            rotation: Quat::from_rotation_x(PI * -0.5),
         },
     ));

Migration Guide

• Since we have added a new filed to the Skybox struct, users will need to include ..Default::default() or some rotation value in their initialization code.