Add ability to register remote animation definitions per activity

This introduces a more stable way of setting a remote animation
than using overridePendingTransition: An activity can register
a set of remote animations which is broke down by transition type.
Whenever the activity is involved into such a transition, the
remote animation will be started.

Remote animations take precedence over regular animations, and
prefixOrderIndex in the hierarchy decides precedence within
multiple apps that set remote animation definitions such that
higher apps override lower apps.

Bug: 64674361
Test: go/wm-smoke
Test: Use with launcher
Change-Id: Id300ff62d9f60966ea2609168f6a02860b3de7af