Auto-completion of possible overrides

[bugproof]

when inheriting some types, there is no auto-completion for override

type Derived() =
    inherit Base()

    override __.(no auto-completion here)

also something like "generate overrides" is missing known from C#.

[Krzysztof-Cieslak]

Hey @baronfel, you think generate overrides will be possible/similar to the stuff you've done recently with abstract classes generation?

[baronfel]

We should check this because based on what I have implemented, I think this should work right now