Sort jobs by processed time first

Say you have a dashboard with some jobs you sent. Normally looks like:

job | sent
--- | ---
file.csv | **5pm**
file.csv | 3pm
file.csv | 1pm
file.csv | 11am

However if your 5pm job was scheduled at lunchtime, then it will look
like this:

job | sent
--- | ---
file.csv | 3pm
file.csv | 1pm
file.csv | **5pm**
file.csv | 11am

This is because the jobs are sorted by when they were created, not when
they were sent. It looks wrong.

**For jobs that have already been sent**

This commit changes the sort order to be based on `processed_at`
instead.

**For upcoming jobs**

If a job doesn’t have a `processed_at` time then it’s scheduled, but
hasn’t started yet. Only in this case should we still be sorting by
`created_at`.

app/dao/jobs_dao.py

@@ -37,7 +37,7 @@ def dao_get_jobs_by_service_id(service_id, limit_days=None, page=1, page_size=50
         )
     return Job.query \
         .filter(*query_filter) \
-        .order_by(desc(Job.created_at)) \
+        .order_by(Job.processing_started.desc(), Job.created_at.desc()) \
         .paginate(page=page, per_page=page_size)