Add ConnzSortOption enum (ConnectionId, Start, BytesTo, BytesFrom,
MsgsTo, MsgsFrom, Subscriptions, Pending, Uptime, Idle, LastActivity)
and ConnzSorter static class with Parse(string?) and Sort(IEnumerable<ConnInfo>,
ConnzSortOption, bool) methods.
Add SortBy and SortDescending properties to ConnzFilterOptions and wire
them through ConnzFilterOptions.Parse (?sort= and ?desc= query params).
Add 10 unit tests in ConnzSortTests covering Parse defaults, known values,
unknown string fallback, and sort ordering for key fields.
Go reference: server/monitor_sort_opts.go, server/monitor.go Connz().
