Use Page Object Model for E2E tests

[jeremyckahn]

seeing this selector repeated a bunch makes me think we'll want to utilize the Page Object Model in the future. then we can have a place for these selectors to live for easier maintenance, and also to make the tests easier to write.

the example in the docs isn't super thorough, but what I am imagining is giving us a syntax more like await farmhandPage.endDay() here. likewise we could have easy access to changing pages (farmhandPage.goToField()) and selecting tools (fieldPage.selectWateringCan()) etc. this certainly does not need done in this PR, but it could be a future refactor/optimization to consider

Originally posted by @lstebner in #548 (comment)