Fix: Pop-up dialog for cancelation of the key upload appears on the wrong...

Fix: Pop-up dialog for cancelation of the key upload appears on the wrong screen (EXPOSUREAPP-2915) (#1331)

* Removed submission cancellation dialog and replaced back handler with simple back navigation

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* Readded submission cancellation warning to first fragment in new submission flow

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* Switched back navigation to use findNavController().popBackStack()

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>