Is there a way in Elm to take a local time (such as the string `2019-03-18T09:10:12.4`; **no offset specifed**) and a timezone (such as `Australia/Sydney`) to a possible [Posix](https://package.elm-lang.org/packages/elm/time/latest/Time#Posix) value (i.e, that time converted to UTC), without using ports?

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There's [waratuman/time-extra](https://package.elm-lang.org/packages/waratuman/time-extra/1.1.0/Time-Extra#fromIso8601Date), but it seems to only work on the Date portion. And sadly [rtfeldman/elm-iso8601-date-strings](https://package.elm-lang.org/packages/rtfeldman/elm-iso8601-date-strings/latest) doesn't take [timezones](https://package.elm-lang.org/packages/justinmimbs/timezone-data/latest/).

In JS, there's options such as [moment-tz](https://momentjs.com/timezone/docs/#/using-timezones/parsing-in-zone/) and [date-fns-timezone](https://date-fns.org/v2.0.0-alpha.27/docs/Time-Zones#date-fns-timezone), but it would be much simpler to avoid JS interop for frequent date parsing.