feat(datetime): add animation to adjacent days selection (#30298)

Issue number: internal

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## What is the new behavior?
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this PR. -->
Now when an adjacent day is selected the component will scroll to the
pretended month, as it does when a month change via arrow buttons.

## Changes:
- add styles for active adjacent day;
- scroll animation when adjacentDay is selected;

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

- [md
preview](https://ionic-framework-git-rou-11744-ionic1.vercel.app/src/components/datetime/test/show-adjacent-days?ionic:mode=md)
- [ios
preview](https://ionic-framework-git-rou-11744-ionic1.vercel.app/src/components/datetime/test/show-adjacent-days?ionic:mode=ios
)
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screenshots of how the component looks before and after the change. -->

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Co-authored-by: Maria Hutt <thetaPC@users.noreply.github.com>
Co-authored-by: ionitron <hi@ionicframework.com>