add objectgroup attributes and/invert

add objectgroup attributes and/invert

add a new table Objectgroup_Attributes where we can save additional
attributes for objectgroups (like the Attribut tables for objects).

Adds two new attributes for the groups:
* and
* invert

These will modify the match behaviour for object groups

Add the table to cluster sync, backup and factory reset.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>