This removes the 'use_owner' option feature from rB61c8ed40f5df.
(this wasnt working well when addons are enabled and when switching
workspaces)

Now Addon filtering is just bypassed for Import/Export menus.

Not sure if this patch should remove the Import/Export addons from the
filtering list to reduce noise [this would be wrong since addons in this
category sometimes register not only to the Import/Export menus...]