misc/crush: Add option to support for disabling dangerous command blocking

By default, crush blocks the execution of potentially dangerous
commands (like known hazardous system commands or package
installations).

This change adds an option to support for disabling the dangerous
command blocking, which would be convenient if one operates in a
safe environment or needs to run those commands.

PR: 296282
Reported by: Victor Igumnov <victoriggy@gmail.com>
Pull Request: https://github.com/freebsd/freebsd-ports/pull/547