[graphite] TextureDataBlock holds span of texture proxies

Bug: b/361603237
Change-Id: I6333baab6b31b66015465f8059540889a393b7b3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/896599
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
6 files changed