virgl: resources without any binding can be cached

virgl: resources without any binding can be cached

Certain games create and destroy lots of resources without binding them.
This can take quite a bit of time and even create unneeded
synchronization. However, we know that if a resource was never bound to
anything, it can be cached. This change does that.

Counting the number of uncached allocation with a tabletop simulator trace:
Before: 2967 uncached allocations over the replay
After: 24 uncached allocations over the replay

Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10225>