[ganesh] Buffer to buffer transfer ops block reordering

Because we will use this to update SkMesh buffers and buffer/draw
dependencies aren't tracked we block all reorderings around buffer
transfer tasks.

Bug: skia:12720

Change-Id: I60e0e4599736d89e71072c7e8e9ee8496a1ff506
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/567297
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
8 files changed