chore: Refactor Contact Inbox Builders (#5617)

- Remove duplicate code and move everything to builders
- fixes: #4680

.rubocop.yml

@@ -16,6 +16,7 @@ Metrics/ClassLength:
     - 'app/models/message.rb'
     - 'app/builders/messages/facebook/message_builder.rb'
     - 'app/controllers/api/v1/accounts/contacts_controller.rb'
+    - 'app/controllers/api/v1/accounts/conversations_controller.rb'
     - 'app/listeners/action_cable_listener.rb'
     - 'app/models/conversation.rb'
 RSpec/ExampleLength: