add shadows in examples (#3201)

# Objective

- As mentioned in #3126, shadows need to be readded in examples

## Solution

- Add shadows in examples

examples/3d/3d_scene_pipelined.rs

@@ -117,6 +117,7 @@ fn setup(
             point_light: PointLight {
                 intensity: 1600.0, // lumens - roughly a 100W non-halogen incandescent bulb
                 color: Color::RED,
+                shadows_enabled: true,
                 ..Default::default()
             },
             ..Default::default()
@@ -144,6 +145,7 @@ fn setup(
             point_light: PointLight {
                 intensity: 1600.0, // lumens - roughly a 100W non-halogen incandescent bulb
                 color: Color::GREEN,
+                shadows_enabled: true,
                 ..Default::default()
             },
             ..Default::default()
@@ -171,6 +173,7 @@ fn setup(
             point_light: PointLight {
                 intensity: 1600.0, // lumens - roughly a 100W non-halogen incandescent bulb
                 color: Color::BLUE,
+                shadows_enabled: true,
                 ..Default::default()
             },
             ..Default::default()
@@ -204,6 +207,7 @@ fn setup(
                 far: 10.0 * HALF_SIZE,
                 ..Default::default()
             },
+            shadows_enabled: true,
             ..Default::default()
         },
         transform: Transform {

examples/3d/load_gltf_pipelined.rs

@@ -41,6 +41,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                 far: 10.0 * HALF_SIZE,
                 ..Default::default()
             },
+            shadows_enabled: true,
             ..Default::default()
         },
         ..Default::default()

examples/3d/shadow_biases_pipelined.rs

@@ -69,6 +69,7 @@ fn setup(
             color: Color::WHITE,
             shadow_depth_bias: 0.0,
             shadow_normal_bias: 0.0,
+            shadows_enabled: true,
             ..Default::default()
         },
         ..Default::default()
@@ -90,6 +91,7 @@ fn setup(
             },
             shadow_depth_bias: 0.0,
             shadow_normal_bias: 0.0,
+            shadows_enabled: true,
             ..Default::default()
         },
         transform: Transform::from_matrix(light_transform),

examples/3d/shadow_caster_receiver_pipelined.rs

@@ -93,6 +93,7 @@ fn setup(
             intensity: 0.0,
             range: spawn_plane_depth,
             color: Color::WHITE,
+            shadows_enabled: true,
             ..Default::default()
         },
         ..Default::default()
@@ -112,6 +113,7 @@ fn setup(
                 far: 50.0,
                 ..Default::default()
             },
+            shadows_enabled: true,
             ..Default::default()
         },
         transform: Transform::from_matrix(light_transform),