EZP-22151: Refactor Legacy SE to use Doctrine DBAL

This PR resolves issue https://jira.ez.no/browse/EZP-22151

Continued from https://github.com/ezsystems/ezpublish-kernel/pull/620

Remaining issues from original PR:

- [x] Rename `EzcDatabase` gateway classes to `DatabaseHandler` or `DoctrineDatabase`
- [x] Integration into Symfony DIC
- [x] Evaluate the change of the `rightJoin` query to not use a RIGHT JOIN. Is this semantically correct? The right join seemed unnecessary, since the WHERE clause uses both tables.

### TODO
- [x] ~~Wait for https://github.com/ezsystems/ezpublish-community/pull/105~~ Closed as not needed