chore: Automate SSL with Cloudflare (#12021)

This PR adds support for automatic SSL issuance using Cloudflare when a
custom domain is updated.

- Introduced a cloudflare configuration. If present, the system will
attempt to issue an SSL certificate via Cloudflare whenever a custom
domain is added or changed.
- SSL verification is handled using an HTTP challenge.
- The job will store the HTTP challenge response provided by Cloudflare
and serve it under the /.well-known/cf path automatically.

How to test:

- Create a Cloudflare zone for your domain and copy the Zone ID.
- Generate a Cloudflare API token with the required SSL certificate
permissions.
- Set the Fallback Origin under SSL -> Custom HostName to the Chatwoot
installation.
- Add or update a custom domain and verify that the SSL certificate is
automatically issued.

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

config/routes.rb

@@ -517,6 +517,7 @@ Rails.application.routes.draw do
   get '.well-known/assetlinks.json' => 'android_app#assetlinks'
   get '.well-known/apple-app-site-association' => 'apple_app#site_association'
   get '.well-known/microsoft-identity-association.json' => 'microsoft#identity_association'
+  get '.well-known/cf-custom-hostname-challenge/:id', to: 'custom_domains#verify'
 
   # ----------------------------------------------------------------------
   # Internal Monitoring Routes