Add mozc double sided version.

Change-Id: I3c50b5c3435c3c01c79bfc14c5d605701a423356
Co-authored-by: Takashi Toyoshima <toyoshim@google.com>
Co-authored-by: Shun Ikejima <ikejima@google.com>
Reviewed-by: Eliot Courtney <edcourtney@google.com>

mozc-doublesided/firmware/Core/Inc/hid.h

@@ -0,0 +1,14 @@
+// Copyright 2024 Google Inc.
+// Use of this source code is governed by an Apache License that can be found in
+// the LICENSE file.
+
+#ifndef HID_H_
+#define HID_H_
+
+#include <stdint.h>
+
+void hid_init(void);
+void hid_update(const uint8_t* keys);
+void hid_deinit(void);
+
+#endif  // HID_H_