64 eslint change unused imports from errors to warnings

[perennialAutodidact]

## Description of changes

• Installed and configured the eslint-plugin-unused-imports ESLint plugin

Test steps

• Stop the front and back end dev servers if they're running
• Run yarn install in both packages
• Start the servers again
• Open backend/app.js and comment out the reference to getDirName as pictured below.
• Verify that the linting error for no unused imports appears
• Open frontend/app.jsx and comment out the reference to the Game component as pictured below.
• Verify that the linting error for no unused imports appears

backend	frontend

[russfraze]

For me, the frontend app throws a linting error but the back end does not. This gives me no linting error in the browser.

[perennialAutodidact]

This was working for me, but now it's not. I'm looking into it. It's not a super huge deal if it shows in VSCode as long as it's eventually caught by the pre-commit hook from the other branch, but I won't know until that branch is merged into dev

[perennialAutodidact]

Try hitting Cmd + Shift + P and entering Developer: Restart Extension Host and see if it makes the warnings appear. This fixed it for me.