res_rtp_asterisk: Fix one way audio problems with hold/unhold when using ICE

ICE sessions will now be restarted if sessions are changed to use new sets of
remote candidates.

(closes issue ASTERISK-22911)
Reported by: Vytis Valentinavičius
Review: https://reviewboard.asterisk.org/r/3275/
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Merged revisions 409565 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 409570 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@409587 65c4cc65-6c06-0410-ace0-fbb531ad65f3