feat: Customizable webhook timeout configuration (#12777)

## Summary
- Ability to configure the webhook timeout for Chatwoot self hosted
installations

fixes: https://github.com/chatwoot/chatwoot/issues/12754

config/installation_config.yml

@@ -79,6 +79,11 @@
   display_title: 'System events Webhook URL'
   description: 'The URL to which the system events like new accounts created will be sent'
   locked: false
+- name: WEBHOOK_TIMEOUT
+  value: 5
+  display_title: 'Webhook request timeout (seconds)'
+  description: 'Maximum time Chatwoot waits for a webhook response before failing the request'
+  locked: false
 - name: DIRECT_UPLOADS_ENABLED
   type: boolean
   value: false