[graphite] Add DrawAtlasTest.

Bug: b/361107460
Change-Id: I6d374b3dc0c1e6de826057a96bf001b9da0e8d2e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/896216
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
7 files changed