FS-10666: [mod_callcenter] Adding callcenter_break agent api

FS-10666: [mod_callcenter] Adding callcenter_break agent api

callcenter_break agent <uuid> can be called with an uuid that represents
an outbound session created to call an agent.

The current behavior of mod_callcenter is to keep watching this channel
until it is hangup, once the hangup happens the bridge-agent-end and
member-queue-end events are fired, agent is released on the database
so it can receive more calls and member is also updated on database.

If you do not want to the agent channel hangup to release the agent you can
call this app with the agent session uuid and the agent will be released and
available to receive more calls. This is useful when the agent is located on a
remote freeswitch box and transfer the call internally, the original leg between
the first FreeSWITCH and the remote box remains live and the agent will only be
Available when the original call hangup.