AMI: Add missing VarSet events when a channel inherits variables.

There should be AMI VarSet events when channel variables are inherited by
an outgoing channel.  Also local;2 should generate VarSet events when it
gets all of its channel variables from channel local;1.

ASTERISK-24415 #close
Reported by: Richard Mudgett
Patches:
      jira_asterisk_24415_v12.patch (license #5621) patch uploaded by Richard Mudgett

Review: https://reviewboard.asterisk.org/r/4074/


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@425782 f38db490-d61c-443f-a65b-d21fe96a405b