[BUGFIX] Add frontend preview URL to CSP frame-src directive

Add the URL of the page to be shown in web > view backend module to
the `frame-src` directive of the Content-Security-Policy. This is
required in case the backend URL is different to the frontend URL
that shall be used to preview that page.

The new registry service `PolicyRegistry` is introduced to collect
temporary adjustments to the Content-Security-Policy, which are
applied in the central `PolicyProvider`.

Resolves: #100460
Releases: main
Change-Id: I3f6eb27fc261e4521940a6222499c1c33ae8015d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78473


Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>