9.0 Working with `NodeAggregate` is not easy

[mhsdesign]

Sometimes there is the usecase of having a "global" across dimension identical node, and the closest thing to that is operating on the node aggregate. For example i experimented with replacing the site entity with the node aggregate of the siteNode. This experiment can be found here https://github.com/neos/neos-development-collection/pull/4780.

But this practice doesnt seem to be intentioned and there are multiple stones in ones way on the php api and maybe even deeper in the concept.

I stumbled for example across:

• NodeAggregate does not know it contentRepositoryId (can be achieved via return current($this->nodesByOccupiedDimensionSpacePoint)->subgraphIdentity->contentRepositoryId;)
• node references (of scope aggregate) setting is not straight forward
• node property (of scope aggregate) setting is not straight forward
• node property of scope aggregate reading is not straight forward -> see pr and description https://github.com/neos/neos-development-collection/pull/4779
  • for the case one is interested in a single arbitrary node - for reading its aggregate scoped properties - one must retrieve it via a hack
• creating a node aggregate in all dimensions is not straight forward -> as one needs an $arbitraryRootDimensionSpacePoint and use CreateNodeVariant? https://github.com/neos/neos-development-collection/blob/13ee7bfc51bd44dcd9a60f7d0cfd426043509cf7/Neos.Neos/Classes/Domain/Service/SiteServiceInternals.php#L114-L146
• deleting the node across all dimensions is not straight forward -> as one needs an $arbitraryDimensionSpacePoint https://github.com/neos/neos-development-collection/blob/13ee7bfc51bd44dcd9a60f7d0cfd426043509cf7/Neos.Neos/Classes/Domain/Service/SiteServiceInternals.php#L46-L80