Add a method to force VibrationEffect to repeat or not.

This is for use with APIs that offer a "setLooping" concept independently.
Effects that already repeat will have their repeat index retained or stripped.
Effects that don't repeat will repeat in their entirety.

BUG: 274119451
Test: unit test
Change-Id: Ifc253bdb3f28866586f24a98a12f4037d7fb0428