VLCPlaybackInfoPlaybackTVViewController: Rework playback options

This merge request brings:

• The addition of the subtitles and audio delay options to the tvOS interface.
• Changes to the value selection for interface for both the delay options and the playback speed.

The subtitles delay option is only available for medias having the video type.

This merge request also brings a fix to:

• The default playback speed value that is now properly declared when the application is launched for the first time.

Screenshots

Closes #140 (closed)

Closes #1085 (closed)