Add Bluetooth examples

Co-authored-by: Peter Harper <77111776+peterharperuk@users.noreply.github.com>

pico_w/bt/picow_bt_example_common.h

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) 2022 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/*
+ * \brief Initialise BTstack example with cyw43
+ *
+ * \return 0 if ok
+ */
+int picow_bt_example_init(void);
+
+/*
+ * \brief Run the BTstack example
+ *
+ */
+void picow_bt_example_main(void);