[TASk] Stabilize ModuleMenuCest test

* Wait until content iframe is loaded
* Proceed only if main module elements are visible
* Check for web module only to speed up a bit

Change-Id: If324bfcfd3db80ab5f481909cd053aa2aa201299
Resolves: #75797
Releases: master
Reviewed-on: https://review.typo3.org/47798


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>