Moved option to add custom NDK to Installation

Currently it was presented as separate button.
But since this option is not supposed to be used often, it was moved to
regular 'Installation UI' and hidden a bit as last item appeared.
Renamed API-Level enums to better reflect purpose
Started implementation of UpdateManager + UI
Renamed types after recent file name changes
Implemented beta-working version of UpdateManager

Should support NDK, simulator and runtime libraries