feat(contrib/snmp2cpe): add --port/-P option

[MaineK00n]

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What did you implement:

add --port/-P option to snmp2cpe command

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

$ git clone https://github.com/MaineK00n/vuls-targets.git
$ docker build -t vuls-target:snmp -f vuls-targets/snmp/Dockerfile .
$ docker run --rm -itd -p 1611:161/udp --name vuls-target vuls-target:snmp

$ make build-snmp2cpe
$ snmp2cpe v2c --port 1611 127.0.0.1 juniper-mx960-13-3r9-13 | snmp2cpe convert
{"127.0.0.1":["cpe:2.3:h:juniper:mx960:-:*:*:*:*:*:*:*","cpe:2.3:o:juniper:junos:13.3r9.13:*:*:*:*:*:*:*"]}

Checklist:

You don't have to satisfy all of the following.

• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
• Format your source code by make fmt
• Pass the test by make test
• Provide verification config / commands
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES

Reference

[shino]

🎊