FIX: Show inviter name in email's from field (#13141)

'From' field of the email contained the name of the user who posted the
shared post. Instead, it should contain the name of the inviter.

app/models/topic.rb

@@ -1695,7 +1695,9 @@ class Topic < ActiveRecord::Base
       post_number: 1,
       data: {
         topic_title: self.title,
-        display_username: username
+        display_username: username,
+        original_user_id: user.id,
+        original_username: user.username
       }.to_json
     )
   end