[TASK] Fix phpstan checkFunctionArgumentTypes errors in ext:core Mail

This patch fixes incompatible type usage in function arguments
and is preparatory work for introducing native type hints and
strict mode in all core files.

Releases: master, 10.4
Resolves: #92282
Change-Id: I7eac7f91fe1461a73f2f3dc5cf6988fb91274de1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65665


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Jörg Bösche <typo3@joergboesche.de>
Reviewed-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>