put an arena on GrSurfaceDrawContext

This is part one of two CLs. In this CL, I put a
sk_sp<GrArenas> on GrSurfaceFillContext where GrArenas wraps
a SkArenaAlloc to add ref counting. Creating
a GrOpsTask shares the GrArenas with the ops task. New plumbing
was added to GR_DRAW_OP_TEST_DEFINE to allow a proper
GrSurfaceDrawContext to be passed to GrAtlasTextOp's
GR_DRAW_OP_TEST_DEFINE so the arena will have a proper lifetime.

The second CL will work on replacing GrOpsTask's fAllocators
system with the shared arena.

Change-Id: Ife3be0ab265441cbffab360f2808f5eed86db8b3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/392936
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Herb Derby <herb@google.com>
13 files changed