Suballocate Buffers on Metal #3109
Description
Similar to #2720, we should consider using gpu-alloc to sub-allocate MTLHeaps instead of just creating raw buffers every time. Unlike DX12 though this isn't as obvious of a perf win because metal has a "automatic memory management" lens to it to some APIs, so the change should be benchmarked. It would also be good to consult metal literature to see if MTLHeap is a performance thing or not.