MatTab: selectedTabChange should not fire when the tab is changed programmatically

There should be a way to differentiate **between a UI and a programmaticcally induced tab change**. As of now, both cause the selectedTabChange: EventEmitter to emit.

My case is pretty simple: I want to display the currently opened Tab in the URL:

somePage?openedTab=1
somePage?openedTab=2

But I also want the corresponding tab to open when a URL pointing to a specific tab is navigated to. **Ideally, the [selectedIndex] input should not cause (selectedTabChange) to fire**.

Does this make sense?

Material 8.2.3, Angular 8.2.11

Comienza con el comportamiento del input selectedIndex y del EventEmitter selectedTabChange de MatTab descrito en el issue. Determina cómo distinguir los cambios de UI de los cambios programáticos y, a continuación, verifica que los cambios provocados por la URL no activen la notificación de cambios de UI, mientras que los cambios de pestaña del usuario sí lo hagan.

Escrito por el modelo de indexación a partir del texto del issue.