Metal: Ensure MTLBatch uses context bound shader

Previously the shader associated with a batch was
assigned separately. This meant on occasion, the
incorrect shader was used with the Metal backend.
Updating the shader fetch to use the context bound
shader instead of the batch shader member as per
OpenGL/Vulkan backends.
Also include state change check to be consistent
with OpenGL.

Authored by Apple: Michael Parkin-White

Co-authored-by: Michael Parkin-White <mparkinwhite@apple.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/111112

source/blender/gpu/metal/mtl_batch.mm

@@ -418,8 +418,8 @@ id<MTLRenderCommandEncoder> MTLBatch::bind(uint v_count)
     return nil;
   }
 
-  /* Verify Shader. */
-  active_shader_ = (shader) ? static_cast<MTLShader *>(unwrap(shader)) : nullptr;
+  /* Fetch bound shader from context. */
+  active_shader_ = static_cast<MTLShader *>(ctx->shader);
 
   if (active_shader_ == nullptr || !active_shader_->is_valid()) {
     /* Skip drawing if there is no valid Metal shader.

source/blender/gpu/metal/mtl_state.mm

@@ -143,7 +143,7 @@ void MTLStateManager::set_mutable_state(const GPUStateMutable &state)
     pipeline_state.dirty_flags |= MTL_PIPELINE_STATE_PSO_FLAG;
   }
 
-  if (changed.depth_range[0] != 0 || changed.depth_range[1] != 0) {
+  if (float_as_uint(changed.depth_range[0]) != 0 || float_as_uint(changed.depth_range[1]) != 0) {
     /* TODO remove, should modify the projection matrix instead. */
     mtl_depth_range(state.depth_range[0], state.depth_range[1]);
   }