refactor(usb): Report USB status w/o HID output.

app/include/zmk/usb.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <usb/usb_device.h>
+#include <usb/class/usb_hid.h>
+
+#include <zmk/keys.h>
+#include <zmk/hid.h>
+
+enum usb_dc_status_code zmk_usb_get_status();
+
+#ifdef CONFIG_ZMK_USB
+int zmk_usb_hid_send_report(u8_t *report, size_t len);
+#endif /* CONFIG_ZMK_USB */