Add GrBackendMutableState object to handle shared texture state.

This is will be the main struct used to synchronize changes of certain
texture/image between clients and Skia. With this change we
implement support for the Vulkan shared state as POC.

Bug: skia:10254
Change-Id: I10543357635c347838b193874e4da4496a0dcf06
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/292311
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
21 files changed