[ganesh] Move YUVA image factories with the other image factories.

This matches what we have in Graphite, where all the factory
functions are in the same file.

Change-Id: I720e4c4ac09192a1a6aceeb5868547a5b0ffd17a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/875156
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
3 files changed