Backport EE API parameters for API::Groups

This backports the API parameters for API::Groups from EE to CE,
ensuring both implementations use the same code. EE specific parameters
are wrapped in an `if` statement for two reasons:

1. It allows us to completely disable the parameters in CE.

2. It removes the need for adding a source comment to signal that the
   parameters are EE only.

lib/api/groups.rb

@@ -20,8 +20,19 @@ module API
         optional :share_with_group_lock, type: Boolean, desc: 'Prevent sharing a project with another group within this group'
       end
 
+      if Gitlab.ee?
+        params :optional_params_ee do
+          optional :membership_lock, type: Boolean, desc: 'Prevent adding new members to project membership within this group'
+          optional :ldap_cn, type: String, desc: 'LDAP Common Name'
+          optional :ldap_access, type: Integer, desc: 'A valid access level'
+          optional :shared_runners_minutes_limit, type: Integer, desc: '(admin-only) Pipeline minutes quota for this group'
+          all_or_none_of :ldap_cn, :ldap_access
+        end
+      end
+
       params :optional_params do
         use :optional_params_ce
+        use :optional_params_ee if Gitlab.ee?
       end
 
       params :statistics_params do
@@ -164,6 +175,10 @@ module API
         optional :name, type: String, desc: 'The name of the group'
         optional :path, type: String, desc: 'The path of the group'
         use :optional_params
+
+        if Gitlab.ee?
+          optional :file_template_project_id, type: Integer, desc: 'The ID of a project to use for custom templates in this group'
+        end
       end
       put ':id' do
         group = find_group!(params[:id])