[BUGFIX] Fix the help message of CLI

The help command prints informations about a specific command.
This text is taken from the doc comment by reflection.

Currently the parser expects that type, variable name and comment
are separated by exactly one space, according to our CGL.

Relax the parsing to allow multiple whitespace characters (including tabs)
as separators when fetching the comment for an argument,
to support other coding styles.

Resolves: #59843
Releases: 6.3, 6.2
Change-Id: Id0a9c0ec00bf442adcbd428088744419200a69a0
Reviewed-on: http://review.typo3.org/31106
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>