Input: add device and factory template

src/common/logging/log.h

@@ -89,6 +89,7 @@ enum class Class : ClassType {
     Audio_DSP,         ///< The HLE implementation of the DSP
     Audio_Sink,        ///< Emulator audio output backend
     Loader,            ///< ROM loader
+    Input,             ///< Input emulation
     Count              ///< Total number of logging classes
 };