Split ExtraConfig into compute + control
Split ExtraConfig into compute + control

This allows specialisation of passthrough config between roles.

ExtraConfig has been left so that this patch can merge before the Heat changes
do. The next patch in this series removes ExtraConfig.

Change-Id: Ia90a62f4782b4c796578f098b6896e92715033ab

rdo-management/tripleo,rdo-management/tripleo