Prevent unintentional use of unsafe CLI options

[treiher]

The currently shown warning when using --no-verification is not very prominent and often scrolls out of view very quickly due to other output.

To make it more obvious that --no-verification is unsafe, we should make it mandatory to add the --unsafe option as well when an unsafe option is used. A clear notice should be shown in a bug box that the error might be caused by the use of unsafe options, and that the command must be re-run without unsafe options before a bug is reported.