Re-add jsx-a11y and accessibility fixes

[js0mmer]

Description

This PR adds back jsx-a11y (previously included with react-scripts) and fixes relevant accessibility errors
Accessiblity fixes:

• Made search module hit items accessible
  • they use divs so I assigned a "button" role and a tab index so they can be focused on when tabbing through the page
  • added a listener for enter key pressing down in addition to the mouse down listener
• Replaced improper usage of label element in reports page
  • label is for labeling inputs only
• Added alt tags where needed
• Replaced theme toggle anchor tag in sidebar with button
• Refactored how dragging a course from search into the planner works on the roadmap page
  • desktop version previously relied on mouse down listener to set the course that was actively being dragged
    • this isn't accessible - doesn't work if a user isn't using a mouse
  • made use of the drag start listener and the search slice to set the active course that is being dragged
  • mobile version has enter key listener now
• made profile image a button
• made overlaytriggers on roadmap accessible by using a button and using functional form (which always gets rid of strict mode warnings)

Screenshots

tab.accessibility.mp4

Steps to verify/test this change:

• Verify changes work as expected on staging instance
  • test tab accessibility - use spacebar to start/end drag for drag/drop components and arrow keys to move
  • test dragging from search on roadmap

Final Checks:

• Verify successful deployment

(optional)

• Write tests
• Write documentation

Issues

Closes #415

[github-actions]

Deployed staging instance to https://staging-416.peterportal.org

[SenghoungLim]

I think overall it is great, especially the catalog page. A few things about the roadmap page, (1) I think when a user tab to the drop down menu on the roadmap year, we should have a rectangle to indicate that the tab is there as well for consistent and visual.

(2) I think the same with the select verified and add review:

(3) Lastly, minor thing probably from previous code, we should remove console.log(review):

[js0mmer]

Will merge this as is! Issues with accordion outlines and popover accessibility can be dealt with in a later PR (or two) as discussed in today's meeting since they don't fall under the scope of jsx-a11y lint errors.