Update rect ops to use "op" in their name and return sk_sp.

Change-Id: I757c33d1cd17a7a7dda858f0fc5ab1094e3c2472
Reviewed-on: https://skia-review.googlesource.com/5985
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
35 files changed