[feature] Process connection errors as a text change

Would be nice to have a feature to process connection errors. This way we could use this also as a "ping" service.
I tried this invalid connections:

**INVALID DOMAIN**
HTTPConnectionPool(host='unvalid-domain.com', port=80): Max retries exceeded with url: / (Caused by NewConnectionError(': **Failed to establish a new connection: [Errno -2] Name or service not known'))**

**WEBSERVER IS DOWN**
HTTPConnectionPool(host='domain-without-web.com', port=80): Max retries exceeded with url: / (Caused by ConnectTimeoutError(, **'Connection to domain-without-web.com timed out. (connect timeout=15)'**))

How can we process this outputs, and send a notification?

Main text to process from output:
- Failed to establish a new connection: [Errno -2] Name or service not known'))
- Connection to domain-without-web.com timed out. (connect timeout=15)

Start by examining the reported connection-error outputs for invalid domains and unavailable webservers, then trace how changedetection.io currently handles failed connections and sends notifications. Done means defining how these errors become processable text and produce a notification, including the proposed ping-service behavior.

Written by the indexing model from the issue text.