[Graphite] Add support for purgeNotUsedSinced to ResourceCache.

Bug: b/238611350
Change-Id: I092bc37bf5d8214b59315dfda04c5edf412a7db7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/674337
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
5 files changed