chore: API documentation updates for CSAT surveys (#7255)

- Expose conversation uuid in APIs
- swagger documentation for cast survey update via public/message/update endpoints
- swagger documentation for survey/responses/conversation_uuid endpoint

Fixes: #6328

app/views/public/api/v1/models/_conversation.json.jbuilder

@@ -1,4 +1,5 @@
 json.id resource.display_id
+json.uuid resource.uuid
 json.inbox_id resource.inbox_id
 json.contact_last_seen_at resource.contact_last_seen_at.to_i
 json.status resource.status