Allow usage without postgreSQL

[bwaidelich]

Currently the ESCR cannot be used without PostgreSQL (even if it is just setup and not actually used).

With a Settings.yaml of

Neos:
  EventSourcing:
    EventStore:
      stores:
        'ContentRepository':
          listeners:
            'Neos\ContentGraph\PostgreSQLAdapter\.*': false

we can turn off the listener, but that leads to an exception of

The Event Listener "Neos\ContentGraph\PostgreSQLAdapter\Domain\Projection\HypergraphProjector" is not registered to any of the configured Event Stores.

Removing the class locally leads to other errors, for example because we currently have a hard dependency on the HypergraphProjector in the \Neos\ContentRepository\BehavioralTests\Command\ContentStreamCommandController constructor