fix: menu: fixes keyboard focus and screen reader functionality

[dkilgore-eightfold]

SUMMARY:

Removes tab index from <li> and moves aria role and tab index to their children. Fixing keyboard navigation.

JIRA TASK (Eightfold Employees Only):

ENG-40530
ENG-34525

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:

Pull the PR branch and run yarn and yarn storybook. Verify the Dropdown, Menu and Select stories behave as expected.

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit b7ed41c:

Sandbox	Source
React	Configuration
Vanilla	Configuration

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (main@c4dc4aa). Click here to learn what that means.
Patch has no changes to coverable lines.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #579   +/-   ##
=======================================
  Coverage        ?   84.82%           
=======================================
  Files           ?      792           
  Lines           ?    17115           
  Branches        ?     6030           
=======================================
  Hits            ?    14517           
  Misses          ?     2532           
  Partials        ?       66           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.