CLI: Refactor cli_complete.

* Stop using "_COMMAND NUMMATCHES" on remote consoles.  Using this
  command had doubled the amount of work needed from the Asterisk
  daemon for each completion request.
* Fix code formatting.
* Remove static buffer used to send the command, use the same buffer
  that will receive the results.
* Move sort from ast_cli_display_match_list.

Change-Id: Ie2211b519a3d4bec45bf46e0095bdd01d384cb69