Use constant state in AnimatedVectorDrawable

Complex animated vector drawables can be expensive to load due to
sub-optimal parsing of the String-based pathData. Suffering that penalty
every time the same drawable is loaded (such as material-themed
ProgressBars) is painful.

The new approach caches constant state of both the VectorDrawable (including
the pathData geometry) and the animators (which includes potentially expensive
path-based interpolators).

issue #17366831 Material ProgressBar taking 200+ms to inflate

Change-Id: Iba3b541e24cfce8c07f5aa9fe6aa7d7b92b2fe1c