Add smoke tests for existing components

[ManpreetSL]

Summary

We want to automatically test that each component loads and is rendered.

Approach

• [x] Home (index.tsx)
• [x] Profile
• [x] About

Notes

https://testing-library.com/docs/react-testing-library/example-intro/#quickstart

[ManpreetSL]

ViewHabits hasn't been merged into main yet, so we'll just test what we can for this branch (from main), and then smoke testing ViewHabits can be done in the branch it's in.

[ManpreetSL]

Test setup is seemingly faulty - Can't run .tsx test files for some reason.

[ManpreetSL]

Will also need to add a workaround for Next.js so that it doesn't serve the test files as pages: https://stackoverflow.com/questions/70832134/is-it-possible-to-put-test-files-under-pages-directory-in-next-js