fix(core): rollback slickgrid width UI change & drop ::ms styling

[ghiscoding]

• rollback again fix(core): small UI regression causing column width to be smaller #1973 because it still causes UI issues, so we're pretty much back to the original code (before v9)
• also cleanup SASS files and also remove unnecessary ::ms-* styling since we're no longer supporting any MS IE browsers

[bolt-new-by-stackblitz]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.0%. Comparing base (6a4cbbe) to head (8a8f555).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1977      +/-   ##
==========================================
  Coverage   100.0%   100.0%              
==========================================
  Files           8      195     +187     
  Lines        1580    35920   +34340     
  Branches      452    10647   +10195     
==========================================
+ Hits         1580    35920   +34340     

Flag	Coverage Δ
angular	100.0% <ø> (ø)
universal	100.0% <100.0%> (?)

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