This patch adds a new `max_working_set_exceeded()` check on Metal so that we can display a "System is out of GPU memory" message to the user. Without this, we get obtuse "CommandBuffer failed" errors at render time due to exceeding the size limit of resident resources. Likely fix for T101787 & T102786. Reviewed By: brecht Differential Revision: https://developer.blender.org/D16713