[graphite] Add begin/endRenderPass for Vulkan backend.

Uses vkCmdBeginRendering/vkCmdEndRendering as a shortcut to get this
up and running. Eventually we will move to the renderpass/subpass
interface to give us fuller functionality.

Bug: b/237107064
Change-Id: I789055ebb1e7b408e6287c3f6a131eb521e86a70
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/702378
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
2 files changed