Allow voicemail playback view to scroll

Add the voicemail-related views into the ListView's header view
so that it can scroll.
Also refactored some layouts so that we only inflate the voicemail
views if hasVoicemail() is true

Bug: 16518757
Change-Id: I17fb303efa96c28c6b97e5cfbf5d8b1ef6a0159c