enable users to delete unexpected new folders inside a read-only folder

enable users to delete unexpected new folders inside a read-only folder

let unexpected new folders in read-only folders be read-write

would be done for folders that are inside a read-only folder and cannot
be uploaded because the parent folder is realy read-only

most probably those folders should never have been there

in case they would be read-only, users cannot delete them, in such
situation, letting them be read-write again should really help

Signed-off-by: Matthieu Gallien <matthieu.gallien@nextcloud.com>