Create if-feature "sort"

[avtobiff]

During review it was raised that an if-feature "sort"
should be created for parameters "sort-by", "locale",
and "direction".

All servers might not implement this and if so should
be able to indicate this to clients.

[kwatsen]

I have two minds about this.

On one hand, I feel that if there is a feature statement for one, then there should be a feature statement for all.

On the other hand, already is a mechanism to disable some of these for CF lists, and it’s unclear why it’s not easy to implement for CT lists (given that already servers must be able to have all config in memory, and locale is optional?

In any case, let’s discuss how best to respond on the list.