theme: add doom-darcula

[betareduced]

Summary

Introduce Intellij's Darcula theme to doom themes pack. It requires tree-sitter for more fine grained highlighting. I'm planning to modify it to adapt when tree-sitter is unavailable.

Screenshot

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• [x] I searched the issue tracker and this hasn't been PRed before.
• [x] My changes are not on the do-not-PR list for this project.
• [x] My commits conform to the git conventions.

[hlissner]

I've converted this to a draft for the time being because I'd like for the hard tree-sitter dependency to be removed, but I haven't had the time to figure out what that would entail to write up a formal review. I'll revisit this as soon as I can.

[numkem]

Ive been using this for a while and I quite like it!

[betareduced]

Since I don't have time to modify this, I deleted my forked repo.

If anyone needs it, the theme file is here