Add icmp to autonode firewall

[stephen-soltesz]

This change adds icmp to the ndt-server firewall rule used by the autonode VMs. By allowing icmp we can run traceroute-caller.

While the web ui reports protocol 58 as "ipv6-icmp", this value in the terraform config generates this error:

Error: Error updating Firewall "projects/mlab-sandbox/global/firewalls/ndt-access-ipv6": googleapi: 
Error 400: Invalid value for field 'resource.allowed[1].IPProtocol': 'ipv6-icmp'. Must be one of 
["ah", "all", "esp", "icmp", "ipip", "sctp", "tcp", "udp"] or an IP protocol number between 0 and 255., invalid

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This change is 

[robertodauria]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! 1 of 1 approvals obtained

[robertodauria]

Reviewable status: complete! 1 of 1 approvals obtained