[TASK] Move LinkVars calculation into separate class

The TSFE god object handles too many things. One
part is the calculation of config.linkVars which
is now moved into its own separate class.

Resolves: #96908
Releases: main
Change-Id: I17670f7b127e22d2557173f75583729119e664c9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73523


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>