Cache Typeface for later animation

The Paint#setFontvariationSettings always creates new Typeface instance
from scratch. To avoid unnecessary Typeface creation for the same weight
variant, cache the Typeface and use it later same animation.

Bug: 189867246
Test: atest TextAnimatorTest TextInterpolatorTest

Change-Id: I67ca72f2c54ca9caf4bcf562557ac4f24b44f01e