Add initial cypress tests

[jadlers]

This PR adds cypress to the site for e2e testing.

This PR is in no ways complete yet but I wanted to get some feedback on how the tests are written before continuing adding tests for all pages.

[lydiahallie]

This looks great! Do you happen to know anything about the Dashboard service Cypress provides (as we're moving towards screenshots as well?)

[jadlers]

Haven't used it yet, but I'll definitely look into it!