Add quakec language extension

[schraf]

I created a language extension for Zed to support QuakeC. It is based on the the tree-sitter parser by vkazanov.

[notpeter]

Please sort .gitmodules. In the future if you commit to a branch on your fork (e.g. not main) and check the "Allow Maintainers to make changes" we can fixup things like this.

[notpeter]

Oh man, extensions.toml needs to be resorted too. 🙄

[schraf]

Some day I will learn that 'u' comes after 'm' in the alphabet. 😭

[notpeter]

Luckily the sort thing is only an issue on initial submission future changes are much easier.

Thanks! And congrats on your first Zed extensions.