GPU: Add HQ normals workaround.

This change makes it possible for platforms to only support high quality
normal rendering. This is part of {T82856} where current AMD drivers
running on the polaris architecture does not support the low quality
setting due to a driver bug.

In a next commit the work around will be enabled.

source/blender/gpu/intern/gpu_capabilities.cc

@@ -102,6 +102,11 @@ bool GPU_crappy_amd_driver(void)
   return GCaps.broken_amd_driver;
 }
 
+bool GPU_use_hq_normals_workaround(void)
+{
+  return GCaps.use_hq_normals_workaround;
+}
+
 bool GPU_shader_image_load_store_support(void)
 {
   return GCaps.shader_image_load_store_support;