Add GarageMode settings.

+ Add CarSettings to store keys related to Car platform.
+ Add a settings Activity for CarSettings, currently can be launched in
  KitchenSink app. Later we can move it to the new Settings app.
+ Add relevant garage mode settings.

Change-Id: Iba3b5215a69004c6d7e38ad8a2a22ebd1acc7e1d
16 files changed