New MediaStyle template:

* Remove all media-specific color extraction and colorization logic
* Remove all 'large icon' gradienting logic
* Simplify base (headerless) style to use a LinearLayout instead of tweaking margins
* Make compact media layout a tweak of the base (headerless) layout
* Make big_media layout a tweak of the big_base layout
* Fix an unnecessary swooping animation that happened on expand
* Ensure RTL layout also works

Fixes: 172652345
Test: manual testing w/ updated notify2
Change-Id: I11c1494c0ac32aaf3e9d2010560cc8f1d8c50037