ContentRepository.Core: Get rid of Doctrine DBAL (v2) dependency

[bwaidelich]

The neos/contentgraph-doctrinedbaladapter package currently has the following doctrine/dbal dependencies:

• DbalCheckpointStorage
• DbalSchemaDiff (and *Factory and unit tests)
• ContentStreamProjection (and *Finder)
• WorkspaceProjection (and *Finder)

In addition, it is used in the ContentGraphProjection (and *Finder) of course (which is not directly part of the core but not expected to be implemented by "end users" either!)

This is especially problematic because we rely on the outdated 2.x version of doctrine/dbal even though 4.x is out since a while.

Related: #4227

[bwaidelich]

Ideas:

As discussed in our weekly today, we should

• Move DbalSchemaDiff and DbalCheckpointStorage to separate package neos/dbal-tools(?)
  • that can be tagged with a version compatible with doctrine/dbal v2, v3 and v4
• Replace "doctrine/dbal": "^2" requirements with "doctrine/dbal": "^2 || ^3 || ^4" and add a dependency to that new package in the neos/contentrepository-core and neos/contentgraph-doctrinedbaladapter composer manifests

[bwaidelich]

Will be resolved with #4227