Add UI tests

[lukekarrys]

#125 and #126 were great candidates for testing. The fixes were in the order tracking which is a separate function and inside the state machine when setting tracks. These could be tested independently but it'd be nice to test them as integration tests within the UI. Jest/testing-library are already setup, but this needs to work of isolating the test cases with DOM selectors and possibly stubbing out the youtube apil