AddGlobalNavigationObserver for change of tabs in a tabbed page

[dansiegel]

Discussed in #2853

^{Originally posted by Natpraveen March 30, 2023}
We could see the AddGlobalNavigationObserver observables getting called on creation of the tabs. But when we switch between the tabs the observables are not getting called.

Believe making the existing observable to fire or having a separate observable for tab changes would help having these information in a single place.