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

spec/controllers/public/api/v1/inbox/conversations_controller_spec.rb

@@ -13,6 +13,7 @@ RSpec.describe 'Public Inbox Contact Conversations API', type: :request do
       expect(response).to have_http_status(:success)
       data = response.parsed_body
       expect(data.length).to eq 1
+      expect(data.first['uuid']).to eq contact_inbox.conversations.first.uuid
     end
 
     it 'does not return any private or activity message' do