fix: Accessibility improvements for Dropdown

[kheinrich-eightfold]

SUMMARY:

This PR fixes an accessibility issue surfaced in a few place in the UI with associated JIRA tickets.

GITHUB ISSUE (Open Source Contributors)

JIRA TASK (Eightfold Employees Only):

https://eightfoldai.atlassian.net/browse/ENG-162951
https://eightfoldai.atlassian.net/browse/ENG-162959
https://eightfoldai.atlassian.net/browse/ENG-162978
https://eightfoldai.atlassian.net/browse/ENG-163006
https://eightfoldai.atlassian.net/browse/ENG-163088

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:

[codesandbox-ci]

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[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.12%. Comparing base (15996a2) to head (7ead6e6).

Files with missing lines	Patch %	Lines
src/components/Dropdown/Dropdown.tsx	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1055      +/-   ##
==========================================
+ Coverage   84.10%   84.12%   +0.01%     
==========================================
  Files        1146     1146              
  Lines       20942    20940       -2     
  Branches     7921     7921              
==========================================
+ Hits        17614    17616       +2     
+ Misses       3240     3236       -4     
  Partials       88       88              

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