Add BGR_10A2 support to Ganesh (take 2)

This is no different from the first try but a Chrome-side bug fix has landed:

https://chromium-review.googlesource.com/c/chromium/src/+/2173388 (Map RGBA/BGRA_1010102 to their correct SkColorType equivalents)

TBR=bsalomon@google.com
Bug: 1068416
Change-Id: Ic6ee758b0f0537d83262b0d708f9b7b15a4cb1c7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/286036
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
20 files changed