qt5: Add the possibility of getting version
We provide both the build and runtime version, so if an app was built against poppler 0.65 but running against 0.72, the app can say somewhere in it's about/config dialogs
Running poppler 0.72 (built against 0.65)
This way we can explain to users while some features are not available even if they should be, because the runtime and build time differences sometimes matter