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

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

app/javascript/dashboard/components-next/message/constants.js

@@ -21,6 +21,7 @@ export const SENDER_TYPES = {
   CONTACT: 'Contact',
   USER: 'User',
   AGENT_BOT: 'agent_bot',
+  CAPTAIN_ASSISTANT: 'captain_assistant',
 };
 
 export const ORIENTATION = {