[TASK] Serialize PageRenderer state instead of the entire class

As prepared in #91316, PageRenderer state is now
serialized instead of serializing the entire object,
this means that caches of the importmap are
excluded from serialization.

Resolves: #96709
Related: #91316
Releases: main
Change-Id: I8edde372274c7ea2fbc18bc08bcb9a140939292a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73251


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Benni Mack <benni@typo3.org>