Camera: Video HDR Feature Integration.

Added framework support for camera applications to query supported
video HDR modes and set the required mode.

Change-Id: Ie318e586838a2f035e59e30fa51af35b52f7c886
Camera: Adds support for meta data callbacks

- This change adds a new type of callback
  that will be called when there are pending
  meta data notifications.

Change-Id: I84f5cbafe4f023c7b0efa9ec8620756b0eaa428d