Exposes style and theme data, adds developer option.

Adds support for a String[] return type in ViewDebug; and in addition to that,
the hasAdjacentMapping method can use the String array as means to map a key to
its value.

Adds DEBUG_VIEW_ATTRIBUTES to Settings so that the heavy per-view
computations only affect those who opt in. This setting is used in
CoreSettingsObserver to avoid impacting start time.

Change-Id: I8f507e4e5361414c30d247e8d9815205feb5e91f