Allow formatted durations to contain multiple time units

[seaneagan]

Could allow DurationRounder.roundDuration to return a Map<TimeUnit, int> which could then mapped to a list of formatted Durations, sorted in descending order of TimeUnit, which can then be formatted using a CollectionFormat.

For example:

new Duration(seconds: 19,531)
// ->
{
TimeUnit.HOUR: 5,
TimeUnit.MINUTE: 25,
TimeUnit.MINUTE: 31
}
// ->
["5 hours", "25 minutes", "31 seconds"]
// ->
"5 hours, 25 minutes, and 31 seconds"

Are there any languages where this doesn't work?
Are there any languages where the order should be reversed?