[TASK] Allow to disable CSP headers for a particular site

This change allows to disable CSP headers for a particular site
configured in `sites/<my-site>/csp.yaml` by using the assignment
`enable: false`.

Resolves: #104549
Releases: main, 12.4
Change-Id: I9e17b5658610e5d47915a5e45ca6a33a870e8d76
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/85591


Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Garvin Hicking <gh@faktor-e.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>