impl Eq + Hash for BindGroup/Layout (#17547)

# Objective

Implement `Eq` and `Hash` for the `BindGroup` and `BindGroupLayout`
wrappers.

## Solution

Implement based on the same assumption that the ID is unique, for
consistency with `PartialEq`.

## Testing

None; this should be straightforward. If there's an issue that would be
a design one.

crates/bevy_render/src/render_resource/bind_group.rs

@@ -21,7 +21,10 @@ define_atomic_id!(BindGroupId);
 /// to a [`TrackedRenderPass`](crate::render_phase::TrackedRenderPass).
 /// This makes them accessible in the pipeline (shaders) as uniforms.
 ///
-/// May be converted from and dereferences to a wgpu [`BindGroup`](wgpu::BindGroup).
+/// This is a lightweight thread-safe wrapper around wgpu's own [`BindGroup`](wgpu::BindGroup),
+/// which can be cloned as needed to workaround lifetime management issues. It may be converted
+/// from and dereferences to wgpu's [`BindGroup`](wgpu::BindGroup).
+///
 /// Can be created via [`RenderDevice::create_bind_group`](RenderDevice::create_bind_group).
 #[derive(Clone, Debug)]
 pub struct BindGroup {
@@ -30,13 +33,27 @@ pub struct BindGroup {
 }
 
 impl BindGroup {
-    /// Returns the [`BindGroupId`].
+    /// Returns the [`BindGroupId`] representing the unique ID of the bind group.
     #[inline]
     pub fn id(&self) -> BindGroupId {
         self.id
     }
 }
 
+impl PartialEq for BindGroup {
+    fn eq(&self, other: &Self) -> bool {
+        self.id == other.id
+    }
+}
+
+impl Eq for BindGroup {}
+
+impl core::hash::Hash for BindGroup {
+    fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
+        self.id.0.hash(state);
+    }
+}
+
 impl From<wgpu::BindGroup> for BindGroup {
     fn from(value: wgpu::BindGroup) -> Self {
         BindGroup {

crates/bevy_render/src/render_resource/bind_group_layout.rs

@@ -5,6 +5,14 @@ use core::ops::Deref;
 
 define_atomic_id!(BindGroupLayoutId);
 
+/// Bind group layouts define the interface of resources (e.g. buffers, textures, samplers)
+/// for a shader. The actual resource binding is done via a [`BindGroup`](super::BindGroup).
+///
+/// This is a lightweight thread-safe wrapper around wgpu's own [`BindGroupLayout`](wgpu::BindGroupLayout),
+/// which can be cloned as needed to workaround lifetime management issues. It may be converted
+/// from and dereferences to wgpu's [`BindGroupLayout`](wgpu::BindGroupLayout).
+///
+/// Can be created via [`RenderDevice::create_bind_group_layout`](crate::RenderDevice::create_bind_group_layout).
 #[derive(Clone, Debug)]
 pub struct BindGroupLayout {
     id: BindGroupLayoutId,
@@ -17,7 +25,16 @@ impl PartialEq for BindGroupLayout {
     }
 }
 
+impl Eq for BindGroupLayout {}
+
+impl core::hash::Hash for BindGroupLayout {
+    fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
+        self.id.0.hash(state);
+    }
+}
+
 impl BindGroupLayout {
+    /// Returns the [`BindGroupLayoutId`] representing the unique ID of the bind group layout.
     #[inline]
     pub fn id(&self) -> BindGroupLayoutId {
         self.id