[BUGFIX] Apply TCA migrations for FlexForm in DataHandler

So far TCA migrations for FlexForm were only called in FormEngine
context. In order for DataHandler to always receive migrated TCA, the
migration method is now moved from TcaFlexPrepare to FlexFormTools.

This also fixes TCA type="file" fields inside FlexForm. TcaFlexPrepare
used the TcaPreparation functionality, which would override the TCA
foreign_match_fields with "dummyField" instead if the FlexForm sub key.

In addition, a typo in a parameter name is fixed as a drive-by change.

Resolves: #99756
Releases: main
Change-Id: I07fadeddc26fa93a6fd7aebc6f0c57eac9bfe0a4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77643


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>