Remove old GrVkBuffer class and rename Buffer2 to Buffer.

Bug: skia:11226
Change-Id: I5f507a0d3ffe0a2698b10b0535486986c2a8b5b7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/367977
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
14 files changed