feat: extend var theming implementation

[jhoward-eightfold]

SUMMARY:

Expose additional css vars to further extend varTheme based theming.

GITHUB ISSUE (Open Source Contributors)

JIRA TASK (Eightfold Employees Only):

CHANGE TYPE:

• Bugfix Pull Request
• Feature Pull Request

TEST COVERAGE:

• Tests for this change already exist
• I have added unittests for this change

TEST PLAN:

Visual inspection is necessary to ensure no visual regression

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[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (main@9e708cb). Click here to learn what that means.
Patch has no changes to coverable lines.

Additional details and impacted files

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  Coverage        ?   84.59%           
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  Files           ?      749           
  Lines           ?    16388           
  Branches        ?     5768           
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  Hits            ?    13863           
  Misses          ?     2450           
  Partials        ?       75           

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