Add WebGPU Backend w/ Dawn Support (#3838)

include/mbgl/gfx/dynamic_texture.hpp

@@ -75,7 +75,8 @@ private:
     std::mutex mutex;
 };
 
-#define MLN_DEFER_UPLOAD_ON_RENDER_THREAD (MLN_RENDER_BACKEND_OPENGL || MLN_RENDER_BACKEND_VULKAN)
+#define MLN_DEFER_UPLOAD_ON_RENDER_THREAD \
+    (MLN_RENDER_BACKEND_OPENGL || MLN_RENDER_BACKEND_VULKAN || MLN_RENDER_BACKEND_WEBGPU)
 
 } // namespace gfx
 } // namespace mbgl