users: Don't show Create User form to non-admin users

For non-admin users, the subsubmenu containing both Edit and Create forms is
shown. Removed the subsubmenu so that only the update form is shown.

Signed-off-by: Joseph Nuthalapati <njoseph@thoughtworks.com>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/users/views.py

@@ -123,6 +123,13 @@ class UserUpdate(ContextMixin, SuccessMessageMixin, UpdateView):
         """Return the URL to redirect to in case of successful updation."""
         return reverse('users:edit', kwargs={'slug': self.object.username})
 
+    def get_context_data(self, **kwargs):
+        """Use self.title and the module-level subsubmenu"""
+        context = super(UserUpdate, self).get_context_data(**kwargs)
+        if not is_user_admin(self.request):
+            del context['subsubmenu']
+        return context
+
 
 class UserDelete(ContextMixin, DeleteView):
     """Handle deleting users, showing a confirmation dialog first.