[!!!][TASK] Remove GU GET/POST related methods

\TYPO3\CMS\Core\Utility\GeneralUtility->_GET
\TYPO3\CMS\Core\Utility\GeneralUtility->_GP
\TYPO3\CMS\Core\Utility\GeneralUtility->_GPmerged
\TYPO3\CMS\Core\Utility\GeneralUtility->_POST

Resolves: #101011
Related: #100963
Related: #100053
Related: #99615
Related: #100596
Related: #99633
Releases: main
Change-Id: I16eae6358dba6d03407d0c6e5daf84a41742d9b0
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/79273


Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Benni Mack <benni@typo3.org>