Remove hardcoded calling script in help controller
The Extbase help command controller has the calling
script hardcoded in several places. This may cause
confusion if the calling script was different.
Use the real script from argv0 instead.
This e.g. changes the output to the full path if the cli dispatcher is called with "$PWD/typo3/cli_dispatch.phpsh"
or prepends the PHP binary path if called with "php $PWD/typo3/cli_dispatch.phpsh"