Unify most common form of encoders: returning SkData

... simplification for most call sites

Change-Id: Ieec0f8d358bdcd62b59ecae66b23cd103c7cda28
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1062936
Reviewed-by: Daniel Dilan <danieldilan@google.com>
Reviewed-by: Florin Malita <fmalita@google.com>
Commit-Queue: Mike Reed <mike@reedtribe.org>
23 files changed