Certificates monitoring

### Description

# I am interested in implementing a widget that allows the user to monitor a domain's certificates.

What problem would this feature solve?
> Glance is likely to become my one stop shop for my dashboarding needs and i currently use a script to monitor my certificates. Adding it to glance would be great.

If applicable, what would the configuration for this feature look like?
```yaml
- type: certificates
title: My certs
style: horizontal-cards
feeds:
- url: https://myimmich.lan
title: Immich
- url: https://prox.lan
title: proxmox
```

Are there any existing examples of this feature in other software?
> there are many solution to monitor you certificates, the most interesting/customizable ones are geared toward businesses and cost a lot of money.

No files, tests, or entry points are named. Start by reviewing existing widget implementations and configuration patterns, then determine how certificate feeds and expiry status should be represented; done means a configured certificates widget can monitor the listed domains and display their certificate status.

Written by the indexing model from the issue text.