androidify populated start dates, too

[rfc2822]

See bitfireAT/davx5-ose#133 (comment)

It happens because this code:

            if (duration != null) {
                // Some servers have problems with DURATION, so we always generate DTEND.
                val zonedStart = dtStartDateTime.toZonedDateTime()
                tsEnd = (zonedStart + duration).toInstant().toEpochMilli()
                duration = null
            }

fails when dtStartTime has the new Europe/Kyiv time zone.