Date picker supporting different calendars

[jardakotesovec]

@adamwathan teased bringing date picker to headless-ui (as part of catalyst effort).

I was curious whether you discussed how far you would like to go with international support for different calendars (Gregorian, Buddhist, Islamic, Persian), similar to what react-aria has?

Its great that react-aria team has published framework agnostic date handling library which is supporting their datepicker https://react-spectrum.adobe.com/internationalized/date/index.html . So maybe that could help to provide wide support in headless-ui as well?

Asking for vue.js developer friend :-).

Thank you!