[BUGFIX] Avoid overwriting goToModule in top frame

In case the TYPO3 backend is loaded inside the content frame,
which is a result of a programming error, the inner backend
overwrites state of the outer one, making the backend
unusable because references to javascript singletons
are mixed between outer and inner frame.

Releases: master
Resolves: #94062
Change-Id: Ia3b75d949ec94ebdce317208e87917206769de48
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/68930


Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>