Feat custom propagator

[tacruc]

Cherry-picked from #2440 and targeted to master.
Thanks @gbrousse-recia for development.

Description

A custom Propagator to fix files updates propagation in nested groupfolders.
Based on branch stable25.
Tested on Nextcloud 25.0.6.
Related Issue

maybe #652 and #1787
Motivation and Context

We had synchronization issues between the server and the client when the files were in nested groupfolders. After some research, we noticed that the propagation was not done correctly (groupfolders etags unchanged in the filecache table).

[github-actions]

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[icewind1991]

There shouldn't be a need to propagate changes to parent groupfolders, cross-storage etag/mtime propagation is handled by it's own system. For folders containing other storages, the returned etag is calculated based on the stored etag for that folder and the root-etags for any storage inside the folder.

[skjnldsv]

Last comment by code owner stayed unanswered.
Closing :)

If you will decide to work on this feature again and if it hasn't been fixed or implemented already, feel free to re-open and solve the various conflicts.

Thanks for the interest in Nextcloud and the effort put into this! 🙇