Fix scrolling in the monaco editor

[rchiodo]

For #10952

Problems with scrolling on new line (caused by scroll handler being called before the line was actually there)

Problems with scrolling when typing as opposed to just up/down arrow. (caused by scroll handler not waiting for the text to appear so scrolling to a visible line that gets destroyed)

Also fixed a bug in my style speedup code. Sometimes there are no visible lines. In that case, don't remember the default of 18PX.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

No Coverage information
0.0% Duplication

[codecov-io]

Codecov Report

Merging #11089 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11089      +/-   ##
==========================================
- Coverage   61.42%   61.39%   -0.03%     
==========================================
  Files         597      597              
  Lines       32756    32756              
  Branches     4631     4631              
==========================================
- Hits        20121    20112       -9     
- Misses      11619    11626       +7     
- Partials     1016     1018       +2     

Impacted Files	Coverage Δ
src/datascience-ui/react-common/arePathsSame.ts	75.00% <0.00%> (-12.50%)	⬇️
src/client/common/utils/platform.ts	64.70% <0.00%> (-11.77%)	⬇️
...ence/ipywidgets/localWidgetScriptSourceProvider.ts	88.13% <0.00%> (-3.39%)	⬇️
src/client/linters/pydocstyle.ts	86.66% <0.00%> (-2.23%)	⬇️
src/client/datascience/debugLocationTracker.ts	76.56% <0.00%> (-1.57%)	⬇️
...client/datascience/kernel-launcher/kernelFinder.ts	75.70% <0.00%> (-0.94%)	⬇️
src/client/common/process/proc.ts	14.49% <0.00%> (-0.73%)	⬇️
...ient/datascience/interactive-ipynb/nativeEditor.ts	11.61% <0.00%> (ø)
...atascience/interactive-window/interactiveWindow.ts	15.48% <0.00%> (ø)

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