review and refactor usage of lamba in QObject connect

[ReimarBauer]

On some of the QObjects we use connect with a lambda function.
This is likly not correct and needs to be verified. It surpresses the capabilty of QT to check if a slot exists.
Test coverage should become checked too.

Prefered solution without lambda.

Also a lot of these signals are duplicated. Likly that is not needed when the mainwindow gets referenced in the multiple_flightpath docking widget.

[rohit2p]

can i work on this @ReimarBauer

[ReimarBauer]

You can but it is likly a larger refactoring and the tests are not completed yet, see #2326 (comment)

[rohit2p]

Okey

[ReimarBauer]

Start with referencing the mainwindow in the other components then remove duplicated code parts. Some hints are in the linked PR.