PointerIcon: Load all animation frames using the same resources

It seems like it's possible for display metrics to change while an
animation drawable is being loaded. If that happens, some animation
frames can be a different size than others, which is unexpected.

To avoid this from happening, use a single Resources object to load all
frames from an animation drawable, and hopefully the metrics associated
with the Resources won't change while the frames are being loaded.

Bug: 321324470
Test: speculative fix
Change-Id: I5f9f3b36dd050006bebbaab06f2c17381d3228fa