verdi computer setup could raise the duplicated message in a callback

[khsrali]

Currently, in verdi computer setup if you use the same label of a computer that already exists, you'll notify at the very end of the command when all option are uselessly collected.

One can simply add a callback function for @options_computer.LABEL to raise click.BadParameter in such cases.

Or even better, get a confirmation from user to do the same thing as verdi computer duplicate

[khsrali]

related #4981
would be nice to address this as well #5018