[BUGFIX] Fix type issues in Request

This patch adds property and return types to the core Request class.
Parameter types cannot be added to methods from RequestInterface
as it has no typed version yet.

Doing so allows for the removal of a lot of now-unnecessary tests
as well as PHPstan baseline issues.

This patch also notes, but does not correct, the incorrect
implementation of getUri(), which this implementation permits
to return null even though that is a PSR-7 violation. Fixing
that has several knock-on effects better addressed in
future patches.

Resolves: #97620
Releases: main
Change-Id: I9b754a261b77fa8fdb6fa58706edf8a5c5248be4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74634


Tested-by: Daniel Haupt <mail@danielhaupt.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Daniel Haupt <mail@danielhaupt.de>
Reviewed-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Reviewed...