move users method to public section

this is for EE to be able to call this (elastic search)

lib/gitlab/search_results.rb

@@ -87,6 +87,12 @@ module Gitlab
       1001
     end
 
+    def users
+      return User.none unless Ability.allowed?(current_user, :read_users_list)
+
+      UsersFinder.new(current_user, search: query).execute
+    end
+
     private
 
     def projects
@@ -137,12 +143,6 @@ module Gitlab
     end
     # rubocop: enable CodeReuse/ActiveRecord
 
-    def users
-      return User.none unless Ability.allowed?(current_user, :read_users_list)
-
-      UsersFinder.new(current_user, search: query).execute
-    end
-
     def default_scope
       'projects'
     end