USE-188: Responsive behavior for tab bar

[djanelle-mit]

Developer

Implements responsive behavior for our tab bar. When the screen is too narrow, a "more" button is created with an overflow menu beneath it.

This work also includes final names, approved by UXWS, for our tabs.

Notable includes in this work:

• I had to add a condition to the loading spinner JS to stop it from firing when buttons or li elements were clicked. It now only fires when a link is clicked.
• This adds a new JS file, and I'm not sure if there's anything I missed when implementing that.
• Keyboard navigation works via TAB key. In <select> dropdown menus up and down keys are how folks navigate, but because this feels like a navigation menu, where tab is typically how folks navigate, it felt right to keep it that way.

Accessibility

• ANDI or WAVE has been run in accordance to our guide.
• This PR contains no changes to the view layer.
• New issues flagged by ANDI or WAVE have been resolved.
• New issues flagged by ANDI or WAVE have been ticketed (link in the Pull Request details above).
• No new accessibility issues have been flagged.

New ENV

• All new ENV is documented in README.
• All new ENV has been added to Heroku Pipeline, Staging and Prod.
• ENV has not changed.

Approval beyond code review

• UXWS/stakeholder approval has been confirmed.
• UXWS/stakeholder review will be completed retroactively.
• UXWS/stakeholder review is not needed.

Additional context needed to review

E.g., if the PR includes updated dependencies and/or data
migration, or how to confirm the feature is working.

Code Reviewer

Code

• I have confirmed that the code works as intended.
• Any CodeClimate issues have been fixed or confirmed as
  added technical debt.

Documentation

• The commit message is clear and follows our guidelines
  (not just this pull request message).
• The documentation has been updated or is unnecessary.
• New dependencies are appropriate or there were no changes.

Testing

• There are appropriate tests covering any new functionality.
• No additional test coverage is required.

[coveralls]

Pull Request Test Coverage Report for Build 19710189968

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.833%

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Totals
Change from base Build 19640498490:	0.0%
Covered Lines:	948
Relevant Lines:	969

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💛 - Coveralls