[BUGFIX] Avoid invalid references in DataMapProcessor

If DataMapProcessor is called with a non-reference id, e.g.
zero (0), this submission is considered as a reference. Since
there is no database record having UID 0, the synchronization
process fails with the following exeception:

	#1486233164: Child record was not processed

To solve this behavior, invalid references (empty/zero) are
not considered anymore to compare references. Besides that,
values for localized records that are configured to be
synchronized are sanitized correctly now.

Resolves: #83009
Releases: master, 8.7
Change-Id: Ie370007521c45dac8bca03978a387b4662952b1d
Reviewed-on: https://review.typo3.org/54655


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>