[BUGFIX] Improve colPos behaviour of SectionViewHelper

Make it possible to render a section menu of content elements
with ignoring the colPos field.

Additionally, a comma separated list of columns can be used
and not only a single colPos.

Resolves: #71733
Releases, master, 7.6
Change-Id: I5f1284ee860c926afd81141d8459efd71cff409d
Reviewed-on: https://review.typo3.org/45999


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>