feat: Add support for realtime-events in copilot-threads and copilot-messages (#11557)

- Add API support for creating a thread
- Add API support for creating a message
- Remove uuid from thread (no longer required, we will use existing
websocket connection to send messages)
- Update message_type to a column (user, assistant, assistant_thinking)

spec/factories/captain/copilot_message.rb

@@ -1,9 +1,8 @@
 FactoryBot.define do
   factory :captain_copilot_message, class: 'CopilotMessage' do
     account
-    user
     copilot_thread { association :captain_copilot_thread }
     message { { content: 'This is a test message' } }
-    message_type { 'user' }
+    message_type { 0 }
   end
 end