Extra Highlight/Cell info

[CrossR]

This just hooks up the last bits of the highlight info from the highlight_set event, so that we can use it in the future for the underline colour and the undercurls.

[codecov]

Codecov Report

Merging #2566 into master will decrease coverage by 0.02%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #2566      +/-   ##
==========================================
- Coverage   45.44%   45.41%   -0.03%     
==========================================
  Files         353      353              
  Lines       14445    14453       +8     
  Branches     1885     1889       +4     
==========================================
  Hits         6564     6564              
- Misses       7657     7665       +8     
  Partials      224      224

Impacted Files	Coverage Δ
browser/src/neovim/NeovimInstance.ts	5.47% <ø> (ø)	⬆️
browser/src/neovim/actions.ts	46.77% <0%> (-1.56%)	⬇️
browser/src/neovim/Screen.ts	4.03% <0%> (-0.21%)	⬇️

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[manu-unter]

Thanks for adding the plumbing here, I would have had to look for the right places to do this for quite some time :)