Add support for linting warnings from godot-gdscript-toolkit

[snorreks]

I'm submitting a...

• Bug report.
• Feature request.

Feature request

It would be great to see the linting warnings for godot-gdscript-toolkit gdlint directly in the editor. I have seen it work in neovim and vscode. This uses the same project as the request in #18.

[gerep]

Doesn't it show to you?

If I hover over the line, it shows the details.

Although I have godot-gdscript-toolkit gdlint installed, it works without it. That's an LSP functionality if I'm not mistaken.

[moomerman]

@gerep I believe what you're seeing there is the LSP warning that the delta variable is unused, which is provided by the LSP but the linter provides other warnings that the LSP can't and it would be useful to have those in the editor as well if possible.