[TASK] Avoid unnecessary null-coalesence operators etc

When PHP 8.0 support was added, a lot of places
received extra checks with the $conf ?? [].

PHPStan complained about this now, as methods
already have native PHP types added now, and the
check is not needed anymore, so it can be simplified

A few other places did not receive proper PHPdoc
annotations which has been fixed as well.

In addition, some str_ends_with calls are migrated.

Resolves: #102528
Releases: main
Change-Id: I031d677473d4e9601fbf9d7c90214c311cfea863
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81975


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>
Tested-by: Andreas Kienast <a.fernandez@scripting-base.de>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>