move sunshine to src

- this will allow for common cpp workflow files within org

src/upnp.h

@@ -0,0 +1,10 @@
+#ifndef SUNSHINE_UPNP_H
+#define SUNSHINE_UPNP_H
+
+#include "platform/common.h"
+
+namespace upnp {
+[[nodiscard]] std::unique_ptr<platf::deinit_t> start();
+}
+
+#endif