feat(report): GitHub security alerts integration

[kotakanbe]

What did you implement:

GitHub tracks reported vulnerabilities in certain dependencies and provides security alerts to affected repositories. GitHub Security Alerts.
It becomes possible to import vulnerabilities detected by GitHub via GitHub 's API.

  [servers.serverA]
    user = "root"
    host = "10.0.0.1"
    port = "22"
    keyPath = "/Users/kanbe/.ssh/id_rsa"
    scanMode = ["fast-root"]

    [servers.serverA.githubs."vulsdoc/vuls"]
    token   = "xxxxYourTokenxxx"

To ignore vulnerabilities dismissed on GitHub, Added -ignore-github-dismissed option to report subcommand.

$ ./vuls report -h                                                                                                 
report:
        report
               ...
                [-ignore-github-dismissed]
               ...

  -ignore-github-dismissed
        Don't report the dismissed CVEs on GitHub Security Alerts
  ...

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce.

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