[BUGFIX] Show correct number of inline records defined in flexform

getRelatedRecordsArray() is expecting comma separated list of record ids
Before this patch the full flexform xml was passed.
Now we detect whether a field is a flexform and try to extract the
correct field values from it.

Resolves: #56882
Releases: master, 6.2
Change-Id: I50db5dfd5f07bbc20e369c0a07f2f294afb85321
Reviewed-on: http://review.typo3.org/32985
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>