DO NOT MERGE Update appcompat themes to inherit from Quantum on L

Introduced the "Theme.Platform" family of themes which
provide an easy way to change the underlying platform
theme for which the rest of appcompat builds upon.

Bug: 15301306

Change-Id: I80face86c8355f16f08732ecf05241f7727ae114
(cherry picked from commit 4e5d70c829208a97e537b87b79f4ade9f315038e)
5 files changed