Extract GrQuadList into separate header

Change-Id: I152ea5a40c4cc65ef5250ca575622a25cf6d1d2a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/216603
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
6 files changed