Feat: Include previous messages in mention/assign notifications email (#3385)

app/drops/conversation_drop.rb

@@ -1,5 +1,17 @@
 class ConversationDrop < BaseDrop
+  include MessageFormatHelper
+
   def display_id
     @obj.try(:display_id)
   end
+
+  def recent_messages
+    @obj.try(:recent_messages).map do |message|
+      {
+        'sender' => message.sender&.available_name || message.sender&.name,
+        'content' => transform_user_mention_content(message.content),
+        'attachments' => message.attachments.map(&:file_url)
+      }
+    end
+  end
 end