Updated Rubocop definitions to work with 0.59.x and code_quality job

There is also a workaround to enable rubocop support integration on a variety of code editors. As gdk-rubocop.yml is not a standard file, many editors will just ignore it and run rubocop with defaults.

Because we only have ruby code in a few folders, we can add a .rubocop.yml file on these folders and inherit from gdk-rubocop.yml.

We can't just rename gdk-rubocop.yml as this would interfere with the configuration file inside the gitlab folder.