Migrate D2ScriptParser to regex builders

[fwcd]

Sadly, we need more than 10 captures, which is the reason why this currently doesn't compile: https://stackoverflow.com/questions/73808600/how-to-capture-more-than-10-things-using-swift-5-7s-regexbuilder

With Swift 5.9's variadic generics arriving, we can only hope that this limitation is soon lifted.