Remove the logic in the HippoAccessManager that grants read access to all nodes below a readable Hippo Document

For historical reasons, every jcr node below a document (a hippo:document below a hippo:handle), is readable/writable if the document is readable/writable for the user.

This means you cannot hide read-access to a certain node below a hippo:document.

There are historical reasons for this why this was done, but after the jcr:path authorization support, we can get rid of it.