Data.Sequence sort functions should be able to inline to eliminate unknown calls.

I'm looking at containers for container-unrelated reasons.

I noticed that some of the sort-related functions (e.g. `popMinQ`) don't have unfoldings available.
This means all comparisons will have to be made by performing unknown calls - yikes.

This extends from `popMinQ` to sort, sortBy at least (and perhaps all the stable sorts).

Now `popMinQ` isn'T small at all at ~400 terms. But I imagine for most use cases it would be beneficial to inline this in order to eliminate the unknown call.

I'm not sure how to best achieve this, but it seems reasonable to me.