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.

Comienza comparando las salidas existentes de monthSelected y yearSelected con el comportamiento de dateChange de MatDatepickerInput; después, inspecciona MatDateRangePicker y DefaultMatCalendarRangeStrategy. El trabajo estará terminado cuando los consumidores puedan observar una selección de rango no aplicada mediante una salida rangeSelected documentada y el comportamiento esté cubierto por las pruebas relevantes del componente.

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