engine: Refactor network compliance enforcement

The motivation of this change is:
1. To decouple network incompatibility auditing from the
network compliance check.
2. To extract clusterNetworks which will be used by the
network interfaces topology persisters in the following
patches.

Change-Id: I5ced33a7ddfe71ea1c69ef5a18cbf468c126ec1c
Signed-off-by: Moti Asayag <masayag@redhat.com>