Add share voicemail functionality.

+Send intent to other applications with temporary file permission
granted
+Add voicemails folder to FileProvider paths
+When creating file in VoicemailArchiveProvider, append extension to
file name
+Check voicemail content exists before archiving it
+Refactor voicemail code
+Add tests for checking file extension
+Add tests for archiving and sharing vociemails
+Archive tab should not archive on share button press

BUG=22798485

Change-Id: Id8068aba92f7f1ca58532dca6c405cb2908841a3