DEV: Extend the reviewables:populate rake task in chat (#30597)

Related to 5a55c9062a

The chat plugin now makes use of the plugin API that was added in the linked commit for extending the reviewables:populate rake task.

plugins/chat/lib/discourse_dev/reviewable_message.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module DiscourseDev
+  class ReviewableMessage < Reviewable
+    def populate!
+      channel = CategoryChannel.new.create!
+      message = Message.new(channel_id: channel.id, count: 1).create!
+      user = @users.sample
+
+      ::Chat::FlagMessage.call(
+        guardian: user.guardian,
+        params: {
+          channel_id: channel.id,
+          message_id: message.id,
+          flag_type_id:
+            ReviewableScore.types.slice(:off_topic, :inappropriate, :spam, :illegal).values.sample,
+        },
+      )
+    end
+  end
+end