[graphite] Add Android Graphite-Vulkan WindowContext creation helper

Bug: b/237108194
Change-Id: Id20b946611bfbe30bcbee592968cf13f11095a6f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/787026
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
4 files changed