Add new experimental API for rectangles with per-edge AA control

Also updates GM_draw_quad_set to use this API instead of the
bulk API on GrRenderTargetContext.

Bug: skia:8506
Change-Id: Ia342d83c509f9db69f06f01599c7041c98aabdb6
Reviewed-on: https://skia-review.googlesource.com/c/184488
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
35 files changed