TIF: Address the feedback from the API review - 1/3

This change addresses the following comments from the council:
- Change TvView.setVolume() --> setStreamVolume()
- Surface only TvInputInfo.getServiceInfo() instead of the separate
  getPackage/getService/getComponent calls.  However, keep loadLabel()
  at the top level.
- @hide register/unregisterListener() for the preview, since it binds
  out to each service.
- TvInputService should document which permission it should protect
  itself with.
- Remove TvInputService.setAvailable() for third-party developers.
- Change class name TvInputSessionImpl --> Session
- Change callback name to onSetStreamVolume() to match earlier change

Bug: 15345342
Change-Id: I3ce5cba7dad2622b78d16c408f81c4b0eba837a4