Important: #65636 - File meta data can now be edited on read only storages

See forge#65636


Whether meta data editing of files is allowed or not must not be bound to whether a file is physically writable in a storage, or whether the storage itself is set read only.

Editing meta data should on the other hand be forbidden, when the file is within a read only file mount.

Allowing meta data editing on read only storage

To allow to distinguish between read access to a file and write access to file meta data, a new file action permission editMeta is introduced, which is automatically checked and enforced when saving a meta data record.

When having to check for editing meta data permission in extension code, it is recommended to use the new file action permission instead of the previously used permission read.