[TASK] Send debug information of cached page as HTTP Header

If config.debug = 1 is added, and a page is loaded
from cache, TYPO3 usually sent
"<!-- Cached page generated 03-09-21 09:48. Expires 04-09-21 09:48 -->"
at the end of the HTTP Response Body.

This is especially painful when dealing with JSON output,
where this breaks output if TYPO3 should return JSON (e.g.
from a USER function).

This change sends the same information as a HTTP
Response Header named "X-TYPO3-Debug-Cache" including
the same information, and not touching the actual rendering.

Resolves: #95103
Releases: master
Change-Id: I737081ae4ac4a079c038c61cc5d37b57e81ab045
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70885


Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Marcin Sągol <marcin@soee.pl>
Reviewed-by: Helmut Hummel <typo3@helhum.io>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Guido Schmechel <guido.schmechel@brandung.de>
Tested-by: Helmut Hummel <typo3@helhum.io>