[WIP] Batch highlightining

[Sobak]

This is one big of a mess draft. It's based off a #56 and obviously it will have to be rebased but for now I kept the somehow-original commit history to make it easier to understand the pain process I was going through.

Open questions

1. Do we have any support for tokenizing goto labels? From the quick grep of the codebase, I didn't spot anything like that. I think it could be nice but of course it's outside of the scope for this PR
2. I have a problem with matching variables. Batch allows two variants of syntax: %foo% and %foo - I have created two regex-based rules to match these. However, no matter how I set their priorities, %foo% always gets matched as "comment %foo" and then "comment %" (even though I use \w+). This can be seen in the token dump of small.bat or with the debug formatter
3. What is the delimiter rule used in Shell highlighting for?
4. For whatever reason I can't match just some of the comments in the bit.batch. This one really puzzles me tbh oO it can be seen from the token dump but lemme attach a screenshot to make it even more obvious

pls send help