ari: Add a copy operation for stored recordings

ari: Add a copy operation for stored recordings

This patch adds a new operation for stored recordings, copy. It takes an
existing stored recording and makes a copy of it in the same directory
or a relative directory under the stored recording directory.

/ari/recordings/stored/{recordingName}/copy?destinationRecordingName={copy_name}

This is particularly useful for voicemail-esque applications, which may need to
copy or move recordings around a directory structure.

Review: https://reviewboard.asterisk.org/r/3768/

ASTERISK-24036 #close
Reported by: Sam Galarneau
Tested by: Sam Galarneau
........

Merged revisions 419021 from http://svn.asterisk.org/svn/asterisk/branches/12

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@419022 65c4cc65-6c06-0410-ace0-fbb531ad65f3