feat(MatDateRangePicker): Add selection event

### Feature Description

Add the ability to be notified when the date range selection change but is not yet applied.

The _dateChange_ output of MatDatepickerInput is not a solution because it notify once the range changed AND applied.

Similar to the outputs _monthSelected_ or _yearSelected_ we already have, it could be _rangeSelected_.

### Use Case

A use case for this is would be to preview the current range selection.

For example, because the datepicker it is not a double calendar (like the one in #20613), it is difficult to see when the range starts or end when it spread over several months.


In the meantime, the hack I found is to override the DefaultMatCalendarRangeStrategy with an observable that I reinject in my component to be notified when the range change.

Inizia confrontando gli output esistenti monthSelected e yearSelected con il comportamento di dateChange di MatDatepickerInput, quindi esamina MatDateRangePicker e DefaultMatCalendarRangeStrategy. Il lavoro è completato quando i consumer possono osservare una selezione dell'intervallo non applicata tramite un output rangeSelected documentato e il comportamento è coperto dai test rilevanti del componente.

Scritto dal modello di indicizzazione a partire dal testo della issue.