Add knobs to NNCP to tune the connectivity probes

[qinqon]

What happened:
If the default gw want to be explicitly removed or ICMP is not working at next-hop-address the probes are not going to work as expected.

What you expected to happen:
Probes to run when needed towards what user want to check.

We need to add some knobs to NNCP to activate/deactivate ping and dns proba and also set the address to ping or resolv.

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• NodeNetworkState on affected nodes (use kubectl get nodenetworkstate <node_name> -o yaml):
• Problematic NodeNetworkConfigurationPolicy:
• kubernetes-nmstate image (use kubectl get pods --all-namespaces -l app=kubernetes-nmstate -o jsonpath='{.items[0].spec.containers[0].image}'):
• NetworkManager version (use nmcli --version)
• Kubernetes version (use kubectl version):
• OS (e.g. from /etc/os-release):
• Others:

[mkowalski]

Probes to run when needed towards what user want to check.

Do we want to allow people run systems without default gateway? I think this is the question we need to answer before we implement customization for the ping probe.