[TASK] Extract callbacks from TypoScriptFrontendControllerTest

TypoScriptFrontendControllerTest uses itself as
callback for USER and USER_INT functions. This
does not work anymore since phpunit 10 TestCase
has a basic constructor which fails when TYPO3
creates an object of this class.

Extract those callbacks to an own class.

Resolves: #100475
Related: #100249
Releases: main
Change-Id: I2789bca20cc7fa086521aeb5799c3a9a20e03ab2
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78483


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>