[BUG] Fix tab completion on expression namespaced accessors

[jaychia]

Fixes tab completion for our namespaced accessors:

One crappy part is that it shows some of the @property functions (e.g. def fget) in there. This is because the jedi interpreter/parser is seeing that it could potentially be aliased in the Sphinx path.

Here's where there is a strong assertion about the name having to be @property instead of some alias like we have here. https://github.com/davidhalter/jedi/blob/f7c9ee943390d9d3102b1992c9d3b6c7d224c16c/jedi/parser_utils.py#L341-L345