[BUG] Lack of message when locked image file is removed from preview

This one comes from https://github.com/owncloud/android/pull/4285#issuecomment-1908115473

Steps to reproduce

1. Lock a picture file
2. Open the picture in the app to preview it
3. Remove the picture from the preview

Actual behaviour

Nothing happens

Expected behaviour

An snackbar clarifying that the file could not be removed because it's locked

In the following video, the file land1.jpg is locked. Removing from preview does not give feedback, removing from file list gives feedback:

https://github.com/owncloud/android/assets/14894746/ea5542be-d3be-4857-89fa-f8956fdd09d1

How to lock a file:

• Try to remove a video that is being streamed from server (not a local copy)
• In oC10 servers: Log in an admin account > Settings (top right menu) > General (left menu, admin side) > tick Enable manual file locking in the web interface. Once enabled, every file (not folder) in the list will have an option Lock file available.

Start by reproducing the locked-file removal flow from the preview and compare it with removal from the file list, which already provides feedback. Trace the preview removal entry point and its error handling; done means a snackbar clearly explains that a locked file could not be removed.