fix(datetime): scroll to newly selected date when value changes (#27806)

Issue number: Resolves #26391

---------

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## What is the current behavior?
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When updating the `value` programmatically on an `ion-datetime` after it
has already been created:
- With grid style: The selected date visually updates, but the calendar
does not scroll to the newly selected month.
- With wheel style: The selected date does not visually update, i.e. the
wheels do not move to show the newly selected date.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- Grid style datetimes now scroll to the selected date using the same
animation as when clicking the next/prev month buttons.
- This animation mirrors the behavior in both MUI and native iOS. See
the [design
doc](https://github.com/ionic-team/ionic-framework-design-documents/blob/main/projects/ionic-framework/components/datetime/0003-datetime-async-value.md)
for more information and screen recordings.
- The animation will not occur if the month/year did not change, or when
the datetime is hidden.
- Wheel style datetimes now visually update to the selected date. No
animation occurs, also mirroring native.
- The `parseDate` util has also had its type signatures updated to
account for returning `undefined` when the date string is improperly
formatted. This was missed when the util was refactored to support
multiple date selection.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

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screenshots of how the component looks before and after the change. -->

- Docs PR: https://github.com/ionic-team/ionic-docs/pull/3053
- While this can technically be considered a bug fix, we are merging it
into a feature branch for safety; it's a fairly significant change to
how datetime behaves, and may interfere with custom logic when updating
a datetime's value async.
- Jumping to the newly selected value is handled by replacing everything
[here](https://github.com/ionic-team/ionic-framework/pull/27806/files#diff-4a407530c60e3cf72bcc11acdd21c4803a94bf47ea81b99e757db1c93d2735b8L364-L407)
with `processValue()`. This covers both wheel and grid datetimes.
- `activePartsClone` as a whole was also removed. It was added in
https://github.com/ionic-team/ionic-framework/pull/24244 to enable
changing `activeParts` without triggering a rerender (and thus jumping
to the new value) but since we now want to do that jump, the clone is no
longer needed.
- The animation code might be tricky to follow, so I recorded going
through it:
https://github.com/ionic-team/ionic-framework/assets/90629384/1afa5762-f493-441a-b662-f0429f2d86a7

core/src/components/datetime-button/datetime-button.tsx

@@ -206,6 +206,10 @@ export class DatetimeButton implements ComponentInterface {
      */
     const parsedDatetimes = parseDate(parsedValues.length > 0 ? parsedValues : [getToday()]);
 
+    if (!parsedDatetimes) {
+      return;
+    }
+
     /**
      * If developers incorrectly use multiple="true"
      * with non "date" datetimes, then just select