Reland: Use modern imageDataProc in mskp's SkSharingProc

Original CL: https://skia-review.git.corp.google.com/c/skia/+/1183737

Also includes staging functions to enable landing in Android by keeping old serialization proc implementation.

Change-Id: Ie2a5f9eeba5e080ed0f8f0c3cbd4921d4ed7d23c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1185836
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
Commit-Queue: Kaylee Lubick <kjlubick@google.com>