fix: Fixing grid colors and grays

[bmingles]

• Styleguide didn't have 850 actually mapped.
• dh-gray-100 is mapped to content-bg but doesn't have a Bootstrap gray-xxx counterpart, so I added a Gray-8XX for illustration while we are still mapping things
• Grid row was mapped to dh-gray-200 but should have been dh-gray-300
• I added calculations for the hsl for grays instead of the all zero hue based ones I had before. They are still not exact but closer. I'm looking into fixing the rounding error.

#1572

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3d4499b) 46.71% compared to head (8ba112e) 46.71%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1621   +/-   ##
=======================================
  Coverage   46.71%   46.71%           
=======================================
  Files         583      583           
  Lines       36308    36308           
  Branches     9094     9094           
=======================================
  Hits        16961    16961           
  Misses      19295    19295           
  Partials       52       52           

Flag	Coverage Δ
unit	46.71% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
packages/code-studio/src/styleguide/Colors.tsx	100.00% <ø> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[dsmmcken]

--dh-color-grid-selection-outline-casing fix?