Enable path clipping for View outlines

Clipping Views to Outlines has existed for several releases,
as has providing a Path for shaping Oulines. However, using
a Path-shaped Outline to clip a View against was specifically
disabled internally, due to historical functionality limitations
(prior to enabling Skia for HWUI rendering) as well as performance
concerns.

On current (even relatively low-end) hardware, path clipping is now
sufficiently performant that we are enabling this functionality.
This functionality will be used by AndroidX APIs that enable easier
shaping via paths.

Bug: 201807515
Test: Manual testing including hwui performance tests and CTS
OutlineTest

Change-Id: Ic61d9393cb72c6ad3517954177e5037a383a0c4d