[androidkit] Image shader support

Tangential updates:

 - new encoded input stream Image factory
 - Paint setters now return the object to support a fluent workflow
 - cube demo updated to store face paints instead of colors


Change-Id: I6142a229b18165112ef1fe76acae38bc4b27480d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/410789
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Jorge Betancourt <jmbetancourt@google.com>
10 files changed