[FEAT]: Preserve event timezone

[TuomasKiviaho]

Timezone for output option seems to always override the timezone defined in the calendar/event thus loosing the local time. Would it be possible to have the option unselected this and use the TZID instead in these cases.

It would be nice to have the possibility to carry the actual IANA zone as a trailer for DST rules (in the style of https://tc39.es/proposal-temporal/docs/zoneddatetime.html) which optionally also omits the need for offset