Reduce flakiness by improving some checks to ensure the app is ready.

[gabriellanata]

Changes:

1. Ensures the runloop is fully flushed before continuing
2. Force enables the accessibility engine and waits for it to load if it is the first time loading on a device
3. Improve detection for view did appear to hopefully detect when the window's root view controller has completed appearance better and reduce issues from slow sim boot
4. Check for unfinished animations with the assumption that we can use those for transitions.
5. Adds a new settings object to be able to configure some of these options

[gabriellanata]

/ptal @danielskathyd @HaloZero @marcosgriselli

[gabriellanata]

/rebase