Fix gettext:store_action_names

The Object.const_source_location stopped being reliable since the
zeitwerk changes landed. Each action is expected to define at least one
of the three methods, so a source location of a method should be a
reliable indicator of where the action comes from.

lib/tasks/gettext.rake

@@ -8,21 +8,26 @@ if gettext_find_task
   namespace :gettext do
     task :store_action_names => :environment do
       storage_file = "#{locale_path}/action_names.rb"
-      klasses = Actions::EntryAction
-                .subclasses
-                .uniq
-                .select do |action|
-        src, = Object.const_source_location(action.to_s)
-        src.start_with? @engine.root.to_s
+      instances = Actions::EntryAction
+                  .subclasses
+                  .uniq
+                  .map(&:allocate)
+                  .select do |action|
+        [:plan, :run, :finalize].any? do |method_name|
+          if action.respond_to?(method_name)
+            src, = action.method(method_name).source_location
+            src.start_with? @engine.root.to_s
+          end
+        end
       end
 
-      if klasses.any?
+      if instances.any?
         puts "writing action translations to: #{storage_file}"
 
         File.write storage_file,
                    "# Autogenerated!\n" +
-                   klasses
-                   .map { |klass| %[_("#{klass.allocate.humanized_name}")] }
+                   instances
+                   .map { |instance| %[_("#{instance.humanized_name}")] }
                    .sort
                    .join("\n") + "\n"
       elsif File.exist? storage_file