Add GDScript as language

[pwab]

I wanted to add Godots GDScript to the supported languages. For testing purposes I just copied the python implementation and replaced some keywords and it seems to work fine enough.

As the language files have stated // GENERATED CODE - DO NOT MODIFY BY HAND at the top I came to thinking that those language files are generated somehow. As I couldn't find documenation in how to generate another language I stopped work there.

Are those files somehow generated by converting the available languages from highlight.js? If so there is the 3rd party package highlightjs-gdscript which could be used.

If this is not the way to go then how to add languages to highlight.dart?