Update sinon.js to 9.0.2 to access async fake timers https://sinonjs.org/releases/v9.0.2/fake-timers/ which can then be used with acceptance tests (previously useFakeTimers didn't work with await, e.g. for visit).
Fix the bookmark acceptance test that was time based to use these new fake timers.
Add a fakeTime function that uses moment and the provided date string + timezone to freeze time using useFakeTimers and return a clock.
Add a timeStep function that accepts a clock from fakeTime and a function to run. Once the function is run we call clock.tickAsync(1000) to progress the fake clock forward 1s to progress promises/callbacks.
If the user chooses "Later Today" as the reminder for a bookmark, then edits that bookmark, we should pre-select "Later Today" if that time has not changed (e.g. later is still 6pm). We do this to avoid confusion instead of opening the custom date + time section.
