Installation error message is incorrect when a TLS error occurs

[jnesta-lh]

• I am installing NixOS inside of a corporate environment that terminates TLS. Thus, in order to view a page over HTTPS, a computer has to explicitly trust the corporation's CA.
• Upon booting the installer, Calamares shows the following error:
  • "The system is not connected to the Internet."
• I found the log file at "/home/nixos/.cache/calamares/session.log". It contains the following:
  • "HTTP error QNetworkReply::SslHandshakeFailedError on request for QUrl("https://cache.nixos.org")

Thus, the installation is failing because the NixOS installer does not trust my company's CA. Obviously, this is expected. However, the error message is bugged, because the system is clearly connected to the Internet. So, this appears to be a general-purpose error message that is displayed when any part of internet connectivity fails.

This behavior is confusing for the end-user, so I propose that the error message is made more granular. Specifically, it should have a dedicated error message for not being able to acquire an IP address via DHCP, not being able to resolve DNS, not having TLS, and so on.

[dalto8]

PRs welcome.