TT#66577 add support of SIP peering registrations based on XMLRPC requests

We need to add a possibility to control (add/modify/delete) registrations
for SIP peerings using NGCP-panel. For that to work NGCP-panel uses XMLRPC
requests being sent towards SEMS, which in its turn takes care of work with:
- locally cached map structures:
  * registrations / registrations_peers
  * registration_ltags / registration_ltags_peers
  * registration_timers / registration_timers_peers
- MySQL database (our scope of interest is 'sems_registrations')
- triggering events

Main amount of work is concentrated on interaction with map structures which keep
an actual information on registrations of either subscribers and peerings,
and less amount of work is related to the SQL side.

Basically, the main idea is to add an identifier, which will be used by
NGCP-panel when sending XMLRPC messages to SEMS, which will let SEMS know,
whether it's an event for a usual subscriber or a SIP peering.

Also we take care of loading time, when SEMS retrieves all previously saved data
from the DB using: peer / subscriber auth preferences and loads this to be usable.
A new query has been added for peering type, to let peerings be loadable after restart.

Change-Id: Id471a95ea3f7f57513e1f728ea48fb4b0543bde9

debian/patches/series

@@ -39,3 +39,4 @@ sipwise/upgrade_to_bullseye.patch
 sipwise/port_to_py3k.patch
 sipwise/db_reg_agent_auth_header.patch
 sipwise/skip_outbound_auth_if_credentials_empty.patch
+sipwise/add_support_for_peering_outbound_registration.patch