When using compressed files such as JS / CSS files,
the files are now put in a ".gz" file extension instead
of ".gzip" as this is more wide-spread and possible by default.

Also see
https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types

Resolves: #93182
Releases: main
Change-Id: I27aa2dbf5d36809eb85c77701b47e03cf5618692
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67272

Tested-by: core-ci <typo3@b13.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Mathias Bolt Lesniak <mathias@pixelant.no>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Mathias Bolt Lesniak <mathias@pixelant.no>
Reviewed-by: crell <larry@garfieldtech.com>
Reviewed-by: Benni Mack <benni@typo3.org>