ICMP interconnectivity check

# Background

When I was debugging network issues, I found following checks were often used and might be worthwhile to add as checks:

* Connectivity between two pods on same machine.
* Connectivity between two pods on different machines.
* Connectivity between pod and node on same machine.
* Connectivity between pod and node on different machines.

Each check above should include two ways. That means, one way connectivity doesn't always means ok vice versa.