Reliable VFolder deletion(purge)

[fregataa]

Current version: main(before release 24.03.0)

Currently, the vfolder deletion task is run by aiotools.PersistentTaskGroup.
The steps of the task is like below

1. Update status value of DB vfolders table to PURGE_ONGOING.
2. Request folder deletion to each storage proxy.
3. Delete records of DB vfolders table that has been successfully deleted.

The clients do not get informed when any error occurs during this long-term tasks.
There are several ways to resolve this issue.

• Use BackgroundTask and its server-side response
• Convert folder deletion from blocking response to event-driven pattern (using Redis)
• Update vfolder name before delete-forever to allow creating a new vfolder with the same name

Please leave any other idea.

Related issues:

• Advanced vfolder deletion features (aka trash bin) #767