[BUGFIX] Fix stage changing in workspace preview

Changing stages using the various buttons in
workspace preview module fatals server side
since the request is incomplete.

This is mainly due to the weird ajax dispatching
from class AjaxDispatcher to ActionHandler: This
area needs a major overhaul.

However, patch for issue #100577 already introduced
a hack to hand the current request down. The patch
re-uses this to fix the issue.

Resolves: #101802
Related: #101781
Related: #96904
Related: #100577
Releases: main, 12.4
Change-Id: Ifacf653ed0409891469a168c7bc0c38eaacf183f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/80690


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>