Make activity initialization tasks visible to process creators

https://redmine.teklia.com/issues/8918

The initialize_activity trigger in arkindex.project.triggers should assign the creator of the process to the RQ task, whcih will make every activity initialization visible to process creators in the frontend through the jobs modal.

To make this task more user friendly, a description should also be set, such as Initializing worker activities for process {name or ID}.

The set_progress method could also be used within the RQ task to show a progress bar, like what export_corpus does. Since the task iterates over each worker run of the process, the progress bar could move through i / process.worker_runs.count().