Timezone support for datetime fields

[marisademeglio]

Is your feature request related to a problem? Please describe.

I'm using this CMS as a backend for a small website built via SSG so the owner can maintain it themselves. There is an "events" collection and it's important that they can specify the timezone for an event.

Describe the solution you'd like

A timezone field for the datetime picker.

Describe alternatives you've considered

I could create a select with a few timezones in it and then recalculate datetime value relative to that.

Additional context