(WIP) refactor gpu allocator selection for vulkan

[shailpatels]

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Unsure why the function to select the optimal allocator was causing an issue, changed it something simpler but working to get the examples running and so i could work on testing swapchain recreation

Seems like an interaction with nvidia and vulkan specifically, will try to understand what the original was doing better and why it was causing this error for me: https://github.com/hexops/mach/issues/1352 so ideally the changes are smaller and I'm still using the same checks as before for selecting an allocator.