For each ACL entry, we want to have a field deriving from CustomField<info.magnolia.security.app.dialog.field.AccessControlList.Entry>.
Such a typed field will allow us to refactor the validation logic from the save action to a Vaadin validator.

We don't rebuild the intermediate artificial Node/Adapter structure, but fill the new field directly with ACL entries (in factory).—We still need to pass this map of ACLs as a property of the Item, so that the save action can read it.

We keep the multivalue part "as is", in the factory (add/delete buttons).
We also try to keep the chooser opening "as is", in the factory.
We try to make the field generic to reuse it for URI Access permissions

• settable permission options, optional access-type options, optional chooser pluggability