[UWS] Add PHASE, AFTER and LAST filters on a JobList.

- PHASE: list only jobs in the specified PHASE. If this parameter is repeated
         jobs matching any of the specified phases will be returned.
- AFTER: list jobs created after the specified ISO-8601 date (included).
         If this parameter is repeated, only the most recent date is retained.
- LAST: list the N-th most recently created jobs, ordered by descending
        creation time

These filter parameters are additive: their constraints are joint as with an
AND operator (except for PHASE parameters ; see above).

If no filter is specified, all jobs EXCEPT the ARCHIVED ones are listed. The
only way to list ARCHIVED jobs is to use PHASE=ARCHIVED (with or without other
filter parameters).

The filtering API has been made in a generic manner so that it is easily
possible to create and add new filters. See the interface JobFilter and the
class JobListRefined for more details.