Allow upload ssl certificates for a specifc zone

### The required feature described as a wish

As a User/Admin/Operator I would like to ,upload custom SSL for specific zone

Currently the certificate applies to all the zones once uploaded

The API also doesn't have the zone id parameter

https://cloudstack.apache.org/api/apidocs-4.21/apis/uploadCustomCertificate.html

There is a pr which moves the console proxy configuration from global level to zone level

https://github.com/apache/cloudstack/pull/11415

It would be beneficial for the operator to have certificates at zone level

Start by reading the uploadCustomCertificate API documentation and the related PR #11415, which moves console proxy configuration from global to zone level. Trace how certificate uploads and zone configuration currently connect. Done means operators can upload a custom certificate for one zone without changing certificates for other zones, with the zone ID represented in the API.

Written by the indexing model from the issue text.