EE API entities are wrongly namespaced

From https://docs.gitlab.com/ee/development/ee_features.html#ee-only-features, when a feature is EE-only, it should not be in the EE:: namespace. This namespace is only for modules that we prepend onto CE classes / modules.

Right now all our EE entities are in ee/lib/ee/api/entities/ when a lot of these should just be under ee/lib/api/entities.

There are some here that are correct because they are prepended modules like ee/lib/ee/api/entities/board.rb

Most of these are caused by ignoring the EEOnlyClass cop: .rubocop_todo/gitlab/ee_only_class.yml