Mnesia migration

Added migration for: pubsub_items migration, users, vcard, vcard_search, event_pusher_push_subscription, rosterusers, roster_versio, last, rostergroups, muc_light_occupants, muc_light_config, migrate_muc_light_rooms, migrate_offline_message, migrate_private_storage

Author: vkatsuba

rel/files/mongooseim.cfg

@@ -640,7 +640,7 @@
 {services,
     [
         {service_admin_extra, [{submods, [node, accounts, sessions, vcard, gdpr, upload,
-                                          roster, last, private, stanza, stats]}]},
+                                          roster, last, private, stanza, stats, migration]}]},
         {service_mongoose_system_metrics, [{initial_report, 300000},
                                            {periodic_report, 10800000}]}
     ]