SkAR Java: refactored project structure

1) Changed file paths
2) Added helpers that were missing previously

Bug: skia:
Change-Id: Idb4194fcef815a23277a17670acf46255a47451d
Reviewed-on: https://skia-review.googlesource.com/143680
Reviewed-by: Mike Reed <reed@google.com>
11 files changed