Improve the UX for cookie categories [D7]

copied from D8 version: https://www.drupal.org/project/eu_cookie_compliance/issues/3068670

Summary

The new feature for cookie categories is great, and let sites to be GDPR compliant. However, there is still work to do to ensure it works for users.

• From the end-user point of view, we need a way to display individual cookies with cookie technical name, human name, and description.
• From the administrator point of view, we need a way to manage individual categories and individual cookie informations with a good UX.
• From a developers point of view, the information should be stored in the eu_cookie_compilance.settings configuration entity (as now it does), but in a structured way (now is just text that need to be split by line or by pipe)
• The cookie information individual descriptions should be still translatable.

Solution

• Evolve the admin form to allow to add/edit/delete separately the different Cookie categories and individual cookie information.
• Evolve the eu_cookie_compliance.settings configuration entity to store the cookie categories information in a structured way.
• Refactor the places where cookie compliance categories are read to adapt they to the new format.