[FOLLOWUP][BUGFIX] IRRE: Check if TCA['ctrl']['languageField'] is set

This patch adds missing functional tests for
\TYPO3\CMS\Backend\Controller\FormInlineAjaxController::createAction

Related: #82330
Releases: master, 8.7, 7.6
Change-Id: I61c8c07dd0d2c6a92bb445d7f2b6baee23251f5d
Reviewed-on: https://review.typo3.org/54171


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>