Security code should not depend on implementation details in oak-core

stillalex, I have been looking at the remaining dependencies of the oak security code base to implementation details in oak-core and found the following main categories (in order of frequency):

• dependency to 'plugins' like nodetype/namespace/version/identifier management, read-only (OAK-7499)
• dependency to indexing implementation details (mainly in repository initializers): IndexConstants (OAK-7502), IndexUtils (OAK-7501), hardcoded *IndexProvider (OAK-7500)
• hardcoded RootProviderService and TreeProviderService in SecurityProviderBuilder and the deprecated SecurityProviderImpl
• one usage of ReadWriteVersionManager.getOrCreateVersionHistory in VersionablePathHook
• one usage of RootFactory.createSystemRoot in UserInitializer linked to the setup of indices.

IMO it would be desirable to get rid of these dependencies implementation details (at least in the security code base in an initial stage).