Add RuboCop (linter) workflow

[Matthew Kienow]

Is your feature request related to a problem? Please describe.
Make it easier for contributors and maintainers to ensure code adheres to a proper style and format.

Describe the solution you'd like
Run RuboCop on push to main branch and on pull requests.

• Add .rubocop.yml configuration to the root directory for controlling RuboCop’s behaviour
• Add workflow .github/workflows/rubocop.yml that runs RuboCop on push and pull_request

Describe alternatives you've considered
None

Additional context
N/A

[adfoster-r7]

Would we want this issue moved over to the https://github.com/rapid7/recog-ruby repo? Or should rubocop be applied to both repositories

[Matthew Kienow]

@adfoster-r7 Yes, recog-ruby needs this work. This issue was opened before the repository split. I created a new issue on recog-ruby, and I'm going to leave this open since we have a handful of Ruby scripts in this repository.

[adfoster-r7]

Closed by #579