Fixed various issues and implemented some new features around the new ScanningQueryEngine

This PR contains different commits related to different query-related issues, as follows:
* MODE-2178 - fixed the code for various types of JOINS and also shareable nodes. Enabled back all the previously disabled Tck tests
* MODE-2247 - implemented the `INTERSECT` and `EXCEPT` operations together with several new test cases
* MODE-2209 - implemented the ability to check `READ` permissions for nodes returned from a query, via a new `NodeSequence` implementation
ok, I can remove this buffer. 
Regarding the above `contains` & `add` methods, I think having just 1 `contains` which _adds_ behind the scenes is really weird. Maybe we can use just one - `addIfAbsent` or something.