res_pjsip: Add AMI events for chan_pjsip contact lifecycle changes

Add a new ContactStatus AMI event.
Publish the following status/state changes:
Created
Removed
Reachable
Unreachable
Unknown

Contact URI, new status/state, aor and endpoint names, and the
last qualify rtt result are included in the event.

ASTERISK-25114 #close

Change-Id: Id25aae5f7122facba183273efb3e8f36c20fb61e
Reported-by: George Joseph <george.joseph@fairview5.com>
Tested-by: George Joseph <george.joseph@fairview5.com>