Allow more control over the directory structure in the local storage driver

[abias]

When using the local storage driver, up to now, the plugin creates a really flat directory structure:

root@eassessment1:/archive/local_archiving# ll
total 0
drwxrwxrwx 1 1024 users 346 Jun 25 15:41 job-1
drwxrwxrwx 1 1024 users 316 Jun 26 00:02 job-2
drwxrwxrwx 1 1024 users 368 Jun 26 00:02 job-3
drwxrwxrwx 1 1024 users 364 Jun 26 00:02 job-4
drwxrwxrwx 1 1024 users 336 Jun 26 00:02 job-5
root@eassessment1:/archive/local_archiving# cd job-1
root@eassessment1:/archive/local_archiving/job-1# ll
total 7.2M
-rwxrwxrwx 1 1024 users 251K Jun 25 15:41  local_archiving-activity-backup-20468-20260625-153838.mbz
-rwxrwxrwx 1 1024 users 7.0M Jun 25 15:41 'archive-Dry Run Prüfungskurs-19542-quiz-Demo-Test E-Prüfungen ohne Safe Exam Browser-20468_2026-06-25-15-38-38.zip'

This is generally fine if you just plan to access the archive assets through the GUI.
However, if the admin wants to find a particular archive directly on disk, he is lost.

It would be awesome to (optionally / configurably)

• add the course ID and activity ID to the job's directory name.
• build a small directory tree with a directory labeled with the course ID at top, containing a directory labeled with the actiity ID, containing the job directories