[TASK] Add functional test for imports with forced uids

Adds a functional test to verify imports with forced uids.
The regarding error message for uncompatible forcing sys_file
uids is also shown now after the import is done.

Resolves: #58824
Releases: master, 6.2
Change-Id: If6062866903277ff32eae24354b6fd264fb65600
Reviewed-on: http://review.typo3.org/30141
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>