Add support for the GDQuest GDScript formatter

We made a new [GDScript formatter](https://github.com/GDQuest/godot-gdscript-formatter-tree-sitter) using Rust technologies that make the formatter really fast to build and maintain.

One reason for that was that the great existing community formatter, GDFormat, does not work for us at GDQuest - we use special, uncommon code patterns to build our learning resources that cannot be formatted super well with GDFormat. There are some pieces unsupported GDScript syntax.

Long story short, with the more recent rust technologies, we can make a formatter that more easily supports all or nearly all GDScript syntax by building upon the technology that powers GDScript support in Neovim, Zed, or recent versions of Emacs. And it runs about 3x to 10x faster depending on the file.

This task is about at least documenting how to use the new formatter, and possibly integrating it as an option that ships with the extension if and when possible.