component AP gateway: JID/node ⟺ AP outbox conversion: - convert a combination of JID and optional pubsub node to AP actor handle (see `getJIDAndNode` for details) and vice versa - the gateway now provides a Pubsub service - retrieve pubsub node and convert it to AP collection, AP pagination is converted to RSM - do the opposite: convert AP collection to pubsub and handle RSM request. Due to ActivityStream collection pagination limitations, some RSM request produce inefficient requests, but caching should be used most of the time in the future and avoid the problem. - set specific name to HTTP Server - new `local_only` setting (`True` by default) to indicate if the gateway can request or not XMPP Pubsub nodes from other servers - disco info now specifies important features such as Pubsub RSM, and nodes metadata ticket 363

Those certificates are used to activate TLS for end-2-end testing (to be as
close as possible as production environment), they are used in other containers
needing TLS certificates (notably Prosody).

To generate them, minica has been used. Minica can be found at https://github.com/jsha/minica.

The following commands have been used:

$ minica --domains "server1.test,*.server1.test,server2.test,server3.test,libervia-backend.test,libervia-web.test"
$ chmod 0644 minica.pem server1.test/cert.pem && chmod 0640 server1.test/key.pem

Note that certificates are valid for 2 years and 30 days, so they must be renewed after this delay.