Add more columns to TV metadata to enable newly requested use cases

Added the following columns to the Channels table:
 searchable - Used to hide certain channels from search.
 locked - Used to prevent unauthorized users from watching certain
          channels by requiring passcode.

Added the following columns to the Programs table:
 genre - Used to describe the categorical genre.
 audio_language - Used to list up available audio languages.

Bug: 14833588, Bug: 14123945, Bug: 14069779
Change-Id: Id01483f56ecf3b665e3d4dbcea1a4800ff7f031d