[TASK] Add methods PURGE and BAN in TYPO3\CMS\Core\Http\Request

Add the HTTP methods 'PURGE' and 'BAN' to $supportedMethods, to
support clear cache requests for proxy caches like varnish.

Resolves: #90968
Releases: master, 9.5
Change-Id: I2d4737319d23b362af689eadd21b6c3134a894e4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64093


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Jonas Eberle <flightvision@googlemail.com>
Tested-by: Timo Poppinga <timo.poppinga@zdrei.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Jonas Eberle <flightvision@googlemail.com>
Reviewed-by: Timo Poppinga <timo.poppinga@zdrei.com>
Reviewed-by: Benni Mack <benni@typo3.org>