Relocate protocol files within tmk_core/common/ (#14972)

* Relocate non platform files within tmk_core/common/

* clang

quantum/virtser.h

@@ -0,0 +1,9 @@
+#pragma once
+
+void virtser_init(void);
+
+/* Define this function in your code to process incoming bytes */
+void virtser_recv(const uint8_t ch);
+
+/* Call this to send a character over the Virtual Serial Device */
+void virtser_send(const uint8_t byte);