Custom Theme 1/n: initial structure

This CL is just laying out the groundwork, adding a new Activity and
CustomTheme class as well as a few layouts and strings needed on the UI

Bug: 124796742

Change-Id: I458995b208863a9201dd0ef6e935c8ff030587ed
11 files changed
tree: d60dccd70155e90ec44dc5035d70fb31752d2add
  1. res/
  2. src/
  3. src_override/
  4. Android.mk
  5. AndroidManifest.xml