Bugfix/ Close signature help on scroll

[akinsho]

Currently the signature help remains open if a user scrolls the buffer mid input, causing it to follow the cursor to the wrong position.

This change removes the cursor moved auditTime and adds a scroll observable which closes the signature help on scroll

hopefully fixes #2237

[codecov]

Codecov Report

Merging #2454 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #2454      +/-   ##
==========================================
- Coverage   42.62%   42.62%   -0.01%     
==========================================
  Files         332      332              
  Lines       13212    13213       +1     
  Branches     1736     1736              
==========================================
  Hits         5632     5632              
- Misses       7302     7303       +1     
  Partials      278      278

Impacted Files	Coverage Δ
browser/src/Services/Language/SignatureHelp.ts	20.51% <0%> (ø)	⬆️
...ces/Language/addInsertModeLanguageFunctionality.ts	36.36% <0%> (ø)	⬆️
browser/src/Editor/NeovimEditor/NeovimEditor.tsx	9.36% <0%> (-0.02%)	⬇️

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[bryphe]

Looks good to me! Thanks @akin909 👍