vmi_networking_test: Add masquerade net custom ipv4 CIDR test
vmi_networking_test: Add masquerade net custom ipv4 CIDR test

In addition to the custom CIDR usage, a connectivity check is added to
the VM gateway, confirming that the CIDR is indeed applied.

Signed-off-by: Edward Haas <416ab6a6c3e37a8cab0d365516e79cce8f9be5ad@redhat.com>

stu-gott/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt