[FEATURE] Add new possibility to retrieve session data in TS

Since the session API has been adjusted it is no longer possible
to access FE session data via getData access in TS.
TSFE:fe_user|sesData|myext|mydata

Instead a new an cleaner approach is now available:
session:myext|mydata

Releases: master
Resolves: #80154
Change-Id: I5ea3cf4f20b03176332f28a21b01d1976868a9d4
Reviewed-on: https://review.typo3.org/52320


Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>