Have GrVkUniformBuffers own their descriptor sets.

Locally this looks to have a perf win especially on Android. We no longer
have to update the values in the uniform descriptor every draw. Also since
we essentially have one uniform buffer per draw already, we were making a
descriptor set per draw as well. Now we just tie them to the uniform buffers
and we should end up with about the same amount.

Change-Id: I65c6a8b2ad5c631c4dbb7ea50068f71a0ed4c894
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/276476
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
6 files changed