[!!!][TASK] Harden extbase configuration managers

- Use strict type mode
- Use type hints whereever possible

Releases: master
Resolves: #87628
Change-Id: I97ccf3d4ca66828efbb59b49786eb69e7de3c925
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/59624


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>