Move `ProjectPolicy`-class methods into module

That way the ProjectPolicy class can be extended with this module
before we prepend the EE::ProjectPolicy. This makes the classmethods
available for rules defined in the EE::ProjectPolicy.

app/policies/project_policy.rb

 class ProjectPolicy < BasePolicy
+  extend ClassMethods
+
   READONLY_FEATURES_WHEN_ARCHIVED = %i[
     issue
     list
@@ -20,22 +22,6 @@ class ProjectPolicy < BasePolicy
     cluster
   ].freeze
 
-  def self.create_read_update_admin_destroy(name)
-    [
-      :"read_#{name}",
-      *create_update_admin_destroy(name)
-    ]
-  end
-
-  def self.create_update_admin_destroy(name)
-    [
-      :"create_#{name}",
-      :"update_#{name}",
-      :"admin_#{name}",
-      :"destroy_#{name}"
-    ]
-  end
-
   desc "User is a project owner"
   condition :owner do
     (project.owner.present? && project.owner == @user) ||

app/policies/project_policy/class_methods.rb

+class ProjectPolicy
+  module ClassMethods
+    def create_read_update_admin_destroy(name)
+      [
+        :"read_#{name}",
+        *create_update_admin_destroy(name)
+      ]
+    end
+
+    def create_update_admin_destroy(name)
+      [
+        :"create_#{name}",
+        :"update_#{name}",
+        :"admin_#{name}",
+        :"destroy_#{name}"
+      ]
+    end
+  end
+end