Modal form for ACL editing in the end-user app

There's no reason to go to the admin app in order to change authorizations for the current document.
If the agent has sufficient permissions (is the dataspace owner), having a modal form with `acl:agentGroup x acl:mode` and `acl:agent x acl:mode` matrixes. Changes to them would issue SPARQL updates for the admin SPARQL endpoint that would create/modify the authorizations.