[TASK] Add functional test for exclude field mixup in FormEngine

This patch introduces a functional test that makes sure that the
exclude field mechanism works correctly with inline elements.

Since the problem was already solved by the FormEngine rewrite
no functional changes are made.

The actual bugfix will be added in the TYPO3 6.2 backport.

Resolves: #47359
Releases: master, 6.2
Change-Id: I5a7a2de16d767f854b4d3f89d599deec28266092
Reviewed-on: http://review.typo3.org/20026


Reviewed-by: Jan Helke <typo3@helke.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>