Option to avoid traverse mount points. (Windows / Linux)

### Feature description
Please, add an option to avoid travers mount points when syncing (Windows / Linux / MacOS / ...)

the aim is to be able to avoir syncing OS cyphered folders (example Zone Central) in unencrypted version on the server.

Use case:
A user opens a Zone Central encrypted container that becomes visible as a directory. It's in fact a mount-point. Now, all apps can see the content of the folder as if it was a normal folder.
We need to avoid nextcloud client to enter this zone (mount point) and sync files.

This option should be enforceable by group policies (windows), plist (MAcOS) or config file (Linux)