Cypress integration tests for openebooks.org

Wrote Tests

I wrote a suite of integration tests using Cypress to ensure the stability of the Open eBooks web app. This gave me a chance to do a deep-dive into how Cypress works, its limitations, and how to integrate it with other libraries like mock-service-worker. These tests now run on every push to the ereading-clients monorepo and give engineers confidence that bugs aren't making it into the base branch.