Introduce OpenOrExecuteFileInterface for handling opening executables
When opening various types of "executables" (native binaries, .exe files, shell scripts or .desktop files), show a dialog to ask the user whether to run/execute it or open it as text (in the case of text-based ones). This uses ExecutableFileOpenDialog for KIOWidgets.
This is modelled after OpenWithHandlerInterface.
Add unit test to openurljobtest.
Edited by Ahmad Samir