WIP - Setup Testing Framework

[alexlwn123]

Relates to testing discussion in #804

This is a work in progress. Opening this draft PR for transparency and to invite feedback on this testing strategy.

Made progress in setting up a frontend testing framework. Seems to be working with all of our current dependencies.

Utilizes jest and the React Testing Library.

Strategy

• Utilize the React Testing Library to render each page.
• Override the render function to wrap all components in ReactContexts (see jest/test-utils.jsx). This allows components to be tested in a fairly realistic environment.
• Store snapshots of each page to catch unwanted UI changes.

TODO

• Handle ssr data
• Begin increasing coverage (add more tests)
• Add CI workflow