Documentation popup is confused by inheritance

## Bug description

Hovering an overriden method either shows the documentation of the parent method or the documentations of _all_ "siblings" overriden methods.

Given [this project demo](https://github.com/godotengine/godot-demo-projects/tree/master/2d/platformer), with the following classes:

1. Hovering `_physics_process` in `Actor` shows the documentation of the method in the `Node` class:


2. While hovering `_physics_process` in `Player` shows the documentation of all `_physics_process` methods:


3. Same thing when hovering a direct method call:


## Expected behavior

Case 1: showing the documentation of the parent is great, but honestly unexpected when hovering the method declaration. Showing both parent documentation + method documentation would be perfect.

Case 2: as previously, only the documentations of the parent method(s) and of the actual method should be shown

Case 3: idem, _but_ the more specific documentation (here `Player._physics_process`'s one) should be shown first