Refine SystemUI plugin and animation deps

The PluginCoreLib dependency is not needed by SystemUIAnimationLib, and
can conflict with downstream plugins that might want to use the
animation lib statically. Remove the dependency, and also remove the
animation Proguard rules that were intended to make the animation lib
another shared library for plugins.

Test: m
Bug: 215530220
Change-Id: Ib96e8b0e6f1d4a432c16e699da79ac2de44c9789