feat: partially implement semantic highlight

[rszyma]

Describe the changes and why are you making them

Closes: #34

Checklist

• Update CHANGELOG.md

[rszyma]

todo:

• fix semantic highlight not working the first time it's activated (race condition, need to wait for files to load first)
• make this feature optional, opt-in for the time being, becuase this is not a full semantic highlight. For example numbers in actions e.g. in one-shot still don't get highlighted properly. Also it stops working when there's an error in config, disappearing coloring might be annoying.
• fix this bug - probably something wrong with unicode handling
  

[rszyma]

I kinda dropped the idea of semantic highlighting hugely because tokens flashing with different colors on and off because of error kicking in when typing something. One idea to remove this flashing entirely is to attach semantic highlighting info to parsed tree and given that majority of nodes don't change semantics when typing, it would be pretty reasonable to reuse same semantic highlighting for the same nodes while until parser error is gone. Idk how doable would that be thought.