Function decode_priority_date_time 

pub fn decode_priority_date_time(
    data: &[u8],
    offset: usize,
) -> Result<((Date, Time), usize), Error>

Decode the date-time choice of BACnetPriorityValue at offset, returning the Date, the Time and the offset past the closing tag.

Anything else at offset (another choice, a bare Date) is an error, so a caller can try this first and fall back to the application-tagged choices. Errors follow constructed::tagged.