Cop idea: Prefer `class_methods do` over `module ClassMethods`

[maxjacobson]

Is your feature request related to a problem? Please describe.

No, this is a request for a new cop.

Describe the solution you'd like

When I write the following code:

module Foo
  extend ActiveSupport::Concern

  module ClassMethods
    def bar
      baz
    end
  end
end

Then rubocop-rails will suggest changing the code to the equivalent:

module Foo
  extend ActiveSupport::Concern

  class_methods do
    def bar
      baz
    end
  end
end

Either works, but for teams which would prefer to consistently use one or the other, it would be nice for rubocop-rails to help provide consistency. This should be configurable to prefer either version.

Describe alternatives you've considered

Happy to continue tolerating the inconsistency

Additional context

N/A