QtMir/Application: Implement showSplash() method
This passes liblomiri-app-launch's value whether to show the splash screen or not on to the shell in a common way. Shells might decide based on this whether to show a splash screen at all or not.
This passes liblomiri-app-launch's value whether to show the splash screen or not on to the shell in a common way. Shells might decide based on this whether to show a splash screen at all or not.