Add checkpoint banner grabbing

[Te-k]

Checkpoint has a specific admin protocol that provides the hostname of the firewall, here is a PR adding a module to zgrab to scan and get this hostname. It is based on several tools like this metasploit module

How to Test

./zgrab2 checkpoint

Notes & Caveats

• I am not very familiar with go, so this definitely need some code review
• I have not implemented any integration test as I don't think there is any open source implementation of this protocol. It would be easy to write a python script to reproduce the protocol but then you are testing what you know works, so I don't think it would be very useful
• I am not fully sure the output schema is correct, I have not tested it.

So this PR needs a bit more work from the community before being merged.