feat(datetime): ionChange will only emit from user committed changes (#26083)

resolves #20873 resolves #24452

BREAKING CHANGE

- `ionChange` is no longer emitted when the `value` property of `ion-datetime` is modified externally. `ionChange` is only emitted from user committed changes, such as clicking or tapping a date.

- Datetime no longer automatically adjusts the `value` property when passed an array and `multiple="false"`. Developers should update their apps to ensure they are using the API correctly.