Add option to skip rects to drawImageLattice()

HWUI skips transparent rects when drawing.

When skia draws using bilerp, we will blend
transparent rects with neighboring rects and might
draw a bit of a smudge.

This CL adds the option to skip rects, allowing us
to have compatible behavior with the framework.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2305433002

Review-Url: https://codereview.chromium.org/2305433002
12 files changed