feat(datetime): align active datetime font size with ios 17 (#28738)

Issue number: N/A

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## What is the current behavior?
The active day in a datetime uses the same font size as the other days.

## What is the new behavior?
Increase the font size of the active day to match the iOS 17 spec. 

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

## Other information

| iOS 17 | Ionic |
| ---| ---|
| ![native
ios](https://github.com/ionic-team/ionic-framework/assets/6577830/d26801cf-2771-4c37-b0f0-64b93017b171)
|
![ionic](https://github.com/ionic-team/ionic-framework/assets/6577830/c73deffe-e7bd-4cc3-a3b9-9ebac0a351c8)
|

> [!NOTE]
> In the above screenshot for Ionic I have added `background:
current-color(base);` to the active day. This code should be there for
"today" but it is not due to a bug
([FW-5808](https://ionic-cloud.atlassian.net/browse/FW-5808)).

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Co-authored-by: ionitron <hi@ionicframework.com>