This commit will fix the sorting error that happens when the user is on
the importers index and attempts to sort by the last run or next run. We
add some migrations to add fields that the datatables can use so it can
sort properly. Previously, this was not working because the
last_imported_at and next_import_at fields were actually methods on the
importer_run object and not the importer object.  We are adding a few
callbacks to the importer and importer_run models to ensure that the
fields are properly set when they are called from either the web or the
worker.

Ref:
- #956

CI was getting errors because the versions we were previously using were
deprecated.  This commit updates the actions to the latest versions.

The downloadable files sorting was broken plus, it's not clear now a
downloadable file should be sorted.

This commit will add a guard to the new migrations to ensure that they
do not run if the columns already exist in the database.

This rake task will allow users to re save all their importers.  It
accounts for tenants if it is a Hyku application.

```sh
bundle exec rake bulkrax:resave_importers
```