Support treesitter standard group

[xrisk]

Treesitter defines the standard groups:

@text.diff.add         ; added text (for diff files)
@text.diff.delete      ; deleted text (for diff files)

Would it be possible to define these in the themes?

[siduck]

will do this weekend, anyways for now just define it in hl_add of chadrc

[siduck]

where's it used? shouldnt diffadded etc be enough

[xrisk]

I think difadded is the regex syntax not treesitter.

[siduck]

so there's just those 2 groups?