[graphite] Add caching functionality to ClipAtlasManager Bug: b/388809647 Bug: b/388808216 Change-Id: I9908a0059d4f39cfc2707049afb640d92a95fca9 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/937417 Reviewed-by: Michael Ludwig <michaelludwig@google.com> Commit-Queue: Jim Van Verth <jvanverth@google.com>