Make it possible to await navigate() when using v7_startTransition

[piotrblasiak]

When v7_startTransition is enabled, navigate() is asynchronous, so a lot of things can happen on the screen before the location actually changes (state changes, lazy loading etc).
There should be an easy way to await the location change. Implementing this yourself is made extra difficult since history.listen is no longer available and we are told to use useNavigate and useLocation instead.