* smp server: refactor message delivery to always respond SOK to subscriptions
* refactor ntf subscribe
* cancel subscription thread and reduce service subscription count when queue is deleted
* subscribe rcv service, deliver sent messages to subscribed service
* subscribe rcv service to messages (TODO delivery on subscription)
* WIP
* efficient initial delivery of messages to subscribed service
* test: delivery to client with service certificate
* test: upgrade/downgrade to/from service subscriptions
* remove service association from agent API, add per-user flag to use the service
* agent client (WIP)
* service certificates in the client
* rfc about drift detection, and SALL to mark end of message delivery
* fix test
* fix test
* add function for postgresql message storage
* update migration
* smp server: limit by time the queues to export journal messages for
* pass queue/msg thresholds separately
* reset db connection on errors
* Revert "smp server: limit by time the queues to export journal messages for"
This reverts commit d3bc0cba4b.
* fix test compilation
* flag to expire messages
* improve test
* expire messages newer than quota
* smp server: store messages in PostgreSQL
* stored procedures to write and to expire messages
* function to export messages
* move all message functions to PostgreSQL, remove delete trigger
* comments
* import messages to db
* fix message import, add export
* fix export
* fix export
* fix compilation flags
* import messages line by line
* fix server start with database storage
* fix compilation
* comments
