Create GitHub Action to Run Cypress

[BCerki]

This PR addresses issue:#101

Includes tests? y Rebased on main address to conflicts? y Updated docs? y

Proposed changes:

• Add a github action that runs the cypress test

Additional notes:

• There are some comments on an older version of this PR here: https://github.com/button-inc/digital_marketplace/pull/102
• Pre-testing, the action builds the whole app. The build action also builds the whole app--any way to avoid this duplication? Added this question to #104 to address later
• The action sets off Cypress errors but the test still runs so I think that's not a problem? They mention this behaviour in their docs: