Serve two purposes:
1. refcounting of vulkan handles with associated destruction. When
combined with the trash list, the user can ensure destruction at
the correct time according to the vulkan rules.
2. avoids polluting our API with 32-bit vs 64-bit integer/pointers
differences as exposed through the vulkan API. on 32-bit, vulkan
non-dispatchable handles are 64-bit integers and on 64-bit, they
are pointers.
