feat: Improve Captain interactions, activity messages (#11493)

Show captain messages under the name of the assistant which generated
the message.

- Add support for `Captain::Assistant` sender type
- Add push_event_data for captain_assistants
- Add activity message handler for captain_assistants
- Update UI to show captain messages under the name of the assistant
- Fix the issue where openAI errors when image is sent
- Add support for custom name of the assistant

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/models/message.rb

@@ -197,10 +197,10 @@ class Message < ApplicationRecord
   end
 
   def valid_first_reply?
-    return false unless outgoing? && human_response? && !private?
+    return false unless human_response? && !private?
     return false if conversation.first_reply_created_at.present?
     return false if conversation.messages.outgoing
-                                .where.not(sender_type: 'AgentBot')
+                                .where.not(sender_type: ['AgentBot', 'Captain::Assistant'])
                                 .where.not(private: true)
                                 .where("(additional_attributes->'campaign_id') is null").count > 1