Support for multiple connections

[moufmouf]

To add support for multiple DB connections, we need to:

• Edit Configuration to add the ability to put several connections (just like in Doctrine ORM): (see https://symfony.com/doc/current/doctrine/multiple_entity_managers.html)
• If several connections are passed, use TdbmExtension to dynamically create additional services (TdbmService, Configuration, NamingStrategy)
• Handle DAO autowiring. Either by finding a way to do this automatically or by dynamically creating all DAOs in the container builder (scan tdbm-[connection].lock and create DAOs accordingly in the container)
• Modify the TDBM command to accept a new parameter: the "tdbmService" instance name