add tests to RAI text dashboard importances part 2

[imatiach-msft]

Description

Part 2 of adding tests for RAI text dashboard. Specifically, in this PR we add UI tests for the dropdown and the slider in the RAI text dashboard.

Checklist

• I have added screenshots above for all UI changes.
• I have added e2e tests for all UI changes.
• Documentation was updated if it was needed.

[codecov-commenter]

Codecov Report

Merging #1642 (4cb3b1d) into main (8484fc1) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1642   +/-   ##
=======================================
  Coverage   89.01%   89.01%           
=======================================
  Files         105      105           
  Lines        5489     5489           
=======================================
  Hits         4886     4886           
  Misses        603      603           

Flag	Coverage Δ
unittests	89.01% <ø> (ø)

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[github-actions]

https://responsibleai.blob.core.windows.net/pullrequest/microsoft/responsible-ai-toolbox/ilmat/text-ui-testsv2/dashboard/index.html