Description of problem:

The REST API search endpoint does not seem to support the `order` parameter.
We would like to query bugs ordered by the last_change_time, so that we can safely use offset + limit to advance in time.


Steps to Reproduce:

Using this base query (for bugs with external links):

```
BZQ=https://bugzilla.redhat.com/rest/bug?limit=5&include_fields=summary,id,last_change_time,creation_time&f1=ext_bz_bug_map.ext_bz_bug_id&o1=isnotempty
```

1. curl ${BZQ}&order=Last Updated
2. curl ${BZQ}&order=Last Updated&chfieldfrom=2021-04-04


Actual results:

1. Bugs ordered by creation time
2. Bugs updated after 2021-04-04, ordered by creation time


Expected results:

The bugs should be ordered by their last update time.

To work around that limitation, we need to collect all the bugs and compute what is the last update time.
Then for the next query, we can start over from this date using the `chfieldfrom` parameter.
However this can miss bug that are updated during the collection.


Additional info:

A sort order (ascending/descending) would be useful too.

Setting order to `last_change_time` does not seem to work either.