Move CubemapLayout out of decal code (#19960)

# Objective

- Make bevy_light possible by making it possible to split out
clusterable into bevy_camera

## Solution

- Move cubemap stuff next to cubemap stuff.

## Testing

- 3d_scene runs

Note: no breaking changes thanks to re-exports

crates/bevy_camera/src/primitives.rs

@@ -363,6 +363,42 @@ impl CubemapFrusta {
     }
 }
 
+/// Cubemap layout defines the order of images in a packed cubemap image.
+#[derive(Default, Reflect, Debug, Clone, Copy)]
+pub enum CubemapLayout {
+    /// layout in a vertical cross format
+    /// ```text
+    ///    +y
+    /// -x -z +x
+    ///    -y
+    ///    +z
+    /// ```
+    #[default]
+    CrossVertical = 0,
+    /// layout in a horizontal cross format
+    /// ```text
+    ///    +y
+    /// -x -z +x +z
+    ///    -y
+    /// ```
+    CrossHorizontal = 1,
+    /// layout in a vertical sequence
+    /// ```text
+    ///   +x
+    ///   -y
+    ///   +y
+    ///   -y
+    ///   -z
+    ///   +z
+    /// ```
+    SequenceVertical = 2,
+    /// layout in a horizontal sequence
+    /// ```text
+    /// +x -y +y -y -z +z
+    /// ```
+    SequenceHorizontal = 3,
+}
+
 #[derive(Component, Debug, Default, Reflect, Clone)]
 #[reflect(Component, Default, Debug, Clone)]
 pub struct CascadesFrusta {

crates/bevy_pbr/src/decal/clustered.rs

@@ -32,6 +32,7 @@ use bevy_image::Image;
 use bevy_math::Mat4;
 use bevy_platform::collections::HashMap;
 use bevy_reflect::Reflect;
+pub use bevy_render::primitives::CubemapLayout;
 use bevy_render::{
     extract_component::{ExtractComponent, ExtractComponentPlugin},
     load_shader_library,
@@ -95,42 +96,6 @@ pub struct ClusteredDecal {
     pub tag: u32,
 }
 
-/// Cubemap layout defines the order of images in a packed cubemap image.
-#[derive(Default, Reflect, Debug, Clone, Copy)]
-pub enum CubemapLayout {
-    /// layout in a vertical cross format
-    /// ```text
-    ///    +y
-    /// -x -z +x
-    ///    -y
-    ///    +z
-    /// ```
-    #[default]
-    CrossVertical = 0,
-    /// layout in a horizontal cross format
-    /// ```text
-    ///    +y
-    /// -x -z +x +z
-    ///    -y
-    /// ```
-    CrossHorizontal = 1,
-    /// layout in a vertical sequence
-    /// ```text
-    ///   +x
-    ///   -y
-    ///   +y
-    ///   -y
-    ///   -z
-    ///   +z
-    /// ```
-    SequenceVertical = 2,
-    /// layout in a horizontal sequence
-    /// ```text
-    /// +x -y +y -y -z +z
-    /// ```
-    SequenceHorizontal = 3,
-}
-
 /// Add to a [`PointLight`] to add a light texture effect.
 /// A texture mask is applied to the light source to modulate its intensity,  
 /// simulating patterns like window shadows, gobo/cookie effects, or soft falloffs.