feat: add rswag cop

[andimrob]

This adds a new cop for request specs to ensure they are written using rswag to document their API contracts. This is accomplished by searching for usages of the built in http verb request methods in spec examples, helper functions, and before blocks. Specs written using RSwag should not be using these methods, they should instead be using RSwag built-ins like run_test! or submit_request!

[smudge]

How does it distinguish between API tests and request tests that test ERB endpoints?

[andimrob]

As written it won't distinguish between the two, I hadn't considered that case. However I think if we wanted to write spec for an endpoint that produces html we'd just specify produces 'text/html and not specify anything about the structure of it. In the tests themselves whether using rswag's built in run_test! or our Retail helper submit_request! we will still have access to the response and could assert things about the html from that. So this as written might work for endpoints that respond with other content types.

This approach is perhaps a bit too naive, instead it could try to assert that a request spec is written in a particular structure using methods that come from rswag:

  path 'url_string' do
    ...
    get/post/put/patch/delete 'some_description' do
      ...
      response 'http_status_code', 'some_description' do
        ...
        run_test!
        
        # or

        it 'some_description' do
          submit_request!
        end
      end
    end
  end