[!!!][TASK] remove iframe / navFrameScript and legacy JS functionality

Resolves: #96125
Related: #94058
Releases: main
Change-Id: I34d9fe4c02d2a44d4cfb401e73c49c239264d9c4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72347


Tested-by: Benjamin Franzke <bfr@qbus.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>