BUGFIX: Standalone subscription store via Neos.ContentRepository.Dbal

[mhsdesign]

This pr is a non breaking architecture fix pr to be released with the next patch 9.0.x release.
It introduces a new package which will be installed automatically when updating to that patch.
Few internal classes were moved to that package, most importantly the SubscriptionStore implementation allowing custom standalone cr integration to instantiate that class and boot a cr without requiring the cr registry which requires flow.
The SubscriptionStoreFactory and SubscriptionStoreFactoryInterface have not been moved to that package as they are correctly part of the CR Registry. The core just excepts an SubscriptionStoreInterface instance no factory.

• BUGFIX: Move internal DoctrineSubscriptionStore to Neos\ContentRepository\Dbal

• PATCH: Move neos/eventstore-doctrineadapter dependency to neos/contentrepository-dbal
  Allowing for real dbal independence of the core.

• PATCH: Move internal DbalSchemaDiff and DbalSchemaFactory to Neos\ContentRepository\Dbal
  The core should be independent of dbal. Previously it did hold dbal tools so the dbal content graph can access those as well as other projections. The content graph thus now depends also on the dbal package.

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Checklist

• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[mhsdesign]

so we group now here both the DbalSchemaDiff as well as the subscription store implementation. That makes sense because the subscription store needs the diff... it a little weird that now because the neos/contentgraph-doctrinedbaladapter depends on the diff and thus brings the subscription engine and the dbal doctrine store.
On the other hand this seems like a good cut. A postgres graph can now still use the common dbal subscription engine without fetching the doctrinedbaladapter into the boat ... so 👍