[SECURITY] Do not disclose encryptionKey via InstallTool

The encryptionKey is a secret that must never be sent within any
request, therefore it is now dropped from the editing interface in
"Configure Installation-Wide Options".

The log file writer has been adapted to be aware of the fact that the
encryption key might not be set when TYPO3 has not yet been installed
(which is the case when `vendor/bin/typo3 setup` is executed).

Resolves: #103046
Releases: main, 13.0, 12.4, 11.5
Change-Id: I260a8a2e9af29908543dfe48ac3658d8c45cc440
Security-Bulletin: TYPO3-CORE-SA-2024-004
Security-References: CVE-2024-25119
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82960


Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>