[V2] Merge Open-Pryv.io & Pryv.io Enterprise version

[perki]

Entreprise version of Pryv.io relies on "service-register" (DNS).

Service-register should be rewritten and embedded in service-core with this ability to work in "dnsLess" or "withDns".

• Each service core should be able to answer "legacy register calls" and either redirect/proxy to the user's managing core. This requires the implementation of a database replicated between cores.

The result should be a single service to be launched and associated with existing core instances.

Replication solutions between cores:

1. Use PostgresQL replication capabilities
2. Sqlite
   • https://www.litesync.io/
   • https://litereplica.io/
   • https://rqlite.io/ (MIT License)