Added tests for double get of a ref in C++ object

[tdavidovicNV]

This PR references a problem where an object of type Outter that holds a reference to an object of type Inner (both with intrusive pointers) triggers the double set_py_self error when used like this:

outter = Outter()
print(outter.get_inner().get_name())
print(outter.get_inner().get_name()) # hits abort here

This is referenced in #1111