[Feature Request] Allow editing of DNS Provider configuration/API keys for existing SSL Certificates

Feature Request

Currently, the application lacks the ability to modify the DNS Provider configuration once an SSL certificate has been created. If a user’s DNS API key expires, is rotated for security, or needs to be corrected, there is no mechanism within the UI to update these credentials. This creates a significant bottleneck for maintaining automated renewals via DNS-01 challenges.

Current Behaviour

• Static Configuration: DNS API credentials are "locked" to the certificate upon creation.
• Renewal Failure: When an API key becomes invalid, renewals fail indefinitely with no way to update the underlying credential.
• Manual Overhead: To fix the issue, a user must delete the existing certificate and create a new one.
• Broken Links: Deleting the certificate forces the user to manually re-assign the new certificate to every individual Proxy Host that was previously linked to the old one.

Requested Behaviour

• Edit Functionality: Add an "Edit" option for entries in the Certificates tab.
• Credential Update: Allow users to modify the DNS Provider selection and the Provider Configuration.
• Persistence: Saving these changes should update the underlying configuration for that specific Certificate ID, ensuring that existing Proxy Host assignments remain intact and valid for the next renewal attempt.

Why this helps

• Efficiency: Eliminates the need to manually update dozens of Proxy Hosts just to change a single API string.
• Security: Encourages users to rotate their DNS API keys regularly, as the process would no longer be a destructive administrative task.
• User Experience: Aligns the SSL management workflow with the rest of the application (like Proxy Hosts, Streams, Redirection Hosts), where settings are expected to be editable rather than permanent.
• Reduced Downtime: Prevents certificates from expiring due to "unfixable" credential errors, ensuring services remain accessible and secure.

No files, tests, or entry points are named. Start by tracing the Certificates tab and the certificate persistence and renewal flows to understand where DNS Provider and Provider Configuration are stored. Done means existing certificates can update those values while retaining their certificate ID and Proxy Host assignments.