[feature:gsoc26] Show automatically generated x509 certificates in device admin

Goal

Currently, the X.509 certificate objects that are automatically generated by X.509 certificate generator templates exist in the database but are not linked back to the device in the admin UI, which makes their discovery difficult. Administrators have to manually navigate to the PKI section and search through all certificates to find the ones belonging to a specific device. This issue aims to solve that by surfacing these certificates directly in the device admin page and providing a summary of all automatically generated certificates for the device with links to drill down into the full certificate details.

Background

Issue #1357 called for updating the Django admin so that "certificate details are visible in the device admin" as part of the GSoC test plan for X.509 Certificate Generator Templates. Commit 52c7544 in PR #1378 implements this by adding a certificate_details readonly field to ConfigInline on the device change page, rendering a table with Template name, UUID, Common Name, Status, and a "View Certificate" link. This issue is meant to review and finalize this UI before the PR is merged.

Options discussed

1. Embedded table inside the configuration tab — The certificate details are rendered as a read-only table inline within the existing "Device configuration details" section of the device change page.
   Below is a screenshot of the current draft implementation of this option (from commit 52c7544), showing the Certificate Details table rendered inside the configuration section of the device change page below Templates section:

   

2. Dedicated X.509 certificates tab — Instead of embedding the table in the configuration section, we introduce a separate tab (or admin section) specifically for X.509 certificates. This tab would only appear when the device has X.509 certificates available. The configuration tab would include a link or indicator pointing the user to the X.509 tab for details.