htc: implement remaining htclow::HtclowManagerImpl funcs (mux impls pending)

libraries/libstratosphere/source/htclow/driver/htclow_driver_manager.hpp

@@ -34,6 +34,8 @@ namespace ams::htclow::driver {
 
             Result OpenDriver(impl::DriverType driver_type);
 
+            impl::DriverType GetDriverType();
+
             IDriver *GetCurrentDriver();
 
             void SetDebugDriver(IDriver *driver);