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.

まず、既存の monthSelected および yearSelected の出力と MatDatepickerInput の dateChange の動作を比較し、次に MatDateRangePicker と DefaultMatCalendarRangeStrategy を調査します。コンシューマーがドキュメント化された rangeSelected 出力を通じて未適用の範囲選択を確認でき、関連するコンポーネントテストでその動作がカバーされた時点で作業完了です。

索引モデルが issue の本文から書いたものです。