[FEATURE] Inject site settings into TypoScript constants and TSconfig

YAML configuration set in a site configuration under the main
key "settings:" are now available as TypoScript constants in
templates and as constants in page TSconfig.

This feature is a replacement for the former page TSconfig functionality
"TSFE.constants", which has been removed.
A former replacement approach had to be reverted in v10.1.

Resolves: #91080
Resolves: #91081
Releases: master
Change-Id: Ia5cd4e94049a359a23418c1fdb122a0d5f8c7311
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64128


Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>