Improve GDScript autocompletion for methods

[Lazy-Rabbit-2001]

Implements the part 1 of godotengine/godot-proposals#11079
Check the link for details about the reason why this pr is posted.

[Lazy-Rabbit-2001]

Kinda off-topic, but it surprised me that the back braces will not get overlapped. In previous versions, trying completing your code inside a couple of round brackets will remove the back brace if the completion is about a method or a keyword with (), like this:

print(is_inside_tree() # <- Here the back brace of `is_inside_tree()` is missing, or overlapping with the outer one.

I'm not sure if it is this pr or some other pr in this version that fixed this bug, or maybe it's because I haven't tested edge situation yet. But it seems to be a good sign.

[Calinou]

Kinda off-topic, but it surprised me that the back braces will not get overlapped.

It depends on whether you accept the suggestion with Tab or Enter. See #90723 which changes this behavior to be more predictable.

[Calinou]

Tested locally, it works as expected. Code looks good to me.

This is a nice usability improvement 🙂

[AdriaandeJongh]

Considering the autocomplete popup uses a monospaced font, and the three dots inside function parentheses take up a considerable width, may I suggest using this character instead?

…

[HolonProduction]

This is indeed a nice improvement. I think the usage of … works better:

Looks good to me on code and functionality side. You still need to squash the commits before this can get merged.

[HolonProduction]

Ok, now it's squashed, but could we get a meaningful commit name? E.g. just the title of the PR. If you already squashed you can use amend for it:

git commit --amend -m "Improve GDScript autocompletion for methods"
git push -f