HPCC-11501 DFUPLus should support --version command

Fix version info display problem.

Extend built-in help text.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
Merge pull request #6112 from AttilaVamos/HPCC-11501-fix

HPCC-11501 DFUPLus should support --version command

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>