nautilus-file-operations: Prevent change permission on container directory

Changing permission for *Enclosed Files* also changes current folder
(container) directory permissions.

This change skips the container directory and changes only the permissions
of the contents to match the UI text.

Closes #810
3 jobs for issue810/enclosed-file-permission-fix in 6 minutes and 45 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #395740
flatpak devel

00:05:53

 
  Deploy
passed #395741
review

00:00:52

manual #395742
allowed to fail manual
stop_review