Add Bluetooth examples

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

pico_w/bt/config/lwipopts.h

@@ -0,0 +1,21 @@
+#ifndef _LWIPOPTS_H
+#define _LWIPOPTS_H
+
+// Generally you would define your own explicit list of lwIP options
+// (see https://www.nongnu.org/lwip/2_1_x/group__lwip__opts.html)
+//
+// This example uses a common include to avoid repetition
+#include "lwipopts_examples_common.h"
+
+#if !NO_SYS
+#define TCPIP_THREAD_STACKSIZE 1024
+#define DEFAULT_THREAD_STACKSIZE 1024
+#define DEFAULT_RAW_RECVMBOX_SIZE 8
+#define TCPIP_MBOX_SIZE 8
+#define LWIP_TIMEVAL_PRIVATE 0
+
+// not necessary, can be done either way
+#define LWIP_TCPIP_CORE_LOCKING_INPUT 1
+#endif
+
+#endif