Input: UDP Client to provide motion and touch controls

An implementation of the cemuhook motion/touch protocol, this adds the
ability for users to connect several different devices to citra to send
direct motion and touch data to citra.

Co-Authored-By: jroweboy <jroweboy@gmail.com>

src/input_common/udp/udp.h

@@ -0,0 +1,27 @@
+// Copyright 2018 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <memory>
+#include <unordered_map>
+#include "input_common/main.h"
+#include "input_common/udp/client.h"
+
+namespace InputCommon::CemuhookUDP {
+
+class UDPTouchDevice;
+class UDPMotionDevice;
+
+class State {
+public:
+    State();
+    ~State();
+    void ReloadUDPClient();
+
+private:
+    std::unique_ptr<Client> client;
+};
+
+std::unique_ptr<State> Init();
+
+} // namespace InputCommon::CemuhookUDP