Update Color API

Make the class final because its instances are immutable and
it contained only static methods prior to O. Fix a couple of
typos/issues reported by external developers. Add a new variant
of getComponents() to avoid allocations, as requested by
external dev.

Test: Color_ColorLongTest
Bug: 32984164
Change-Id: I3c22e124c9fdf66142d530afa4beb05fe0669359