## Problem
We need to export some metrics about certs/connections to configure
alerts and make sure that all HTTP requests are gone before turning
https-only mode on.
- Closes: https://github.com/neondatabase/cloud/issues/25526
## Summary of changes
- Add started connection and connection error metrics to http/https
Server.
- Add certificate expiration time and reload metrics to
ReloadingCertificateResolver.
I've encountered this error in #11422. Ideally we'd have the URL as well
to associate it with a tenant, but at this level we only have the remote
addr I guess. Better than nothing.