Environment-specific variables for Group-level variables

Description

We implemented https://gitlab.com/gitlab-org/gitlab-ee/issues/2302 for Project-level variables, we should support Group-level variables as well

Proposal

Implement Environment-specific variables for Group-level variables

Links / references

• https://gitlab.com/gitlab-org/gitlab-ee/issues/2302
• https://gitlab.com/gitlab-org/gitlab-ce/issues/12729

/cc @ayufan @godfat

mentioned in merge request !2373 (merged)

changed milestone to %Backlog

Affected places https://gitlab.com/gitlab-org/gitlab-ee/commit/7988d68705926c20de28a49da76674ca87377a6a

We should also take care of this:

class Variable < Grape::Entity
  expose :key, :value
  expose :protected?, as: :protected

  # EE
  expose :environment_scope, if: ->(variable, options) {
    if variable.respond_to?(:environment_scope)
      variable.project.feature_available?(:variable_environment_scope)
    end
  }
end

I am not creating a separate issue because I guess without this it won't make too much benefit.

removed assignee