Added usb video example

examples/usb-video/common/IpcService.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <libtwl/ipc/ipcFifoSystem.h>
+
+class IpcService
+{
+    const u32 _ipcChannel;
+protected:
+    explicit IpcService(u32 ipcChannel)
+        : _ipcChannel(ipcChannel) { }
+
+    void SendResponseMessage(u32 data) const
+    {
+        ipc_sendFifoMessage(_ipcChannel, data);
+    }
+
+public:
+    virtual void Start();
+    virtual void OnMessageReceived(u32 data) = 0;
+};