Make wifi optional and exclude from nrf52 builds

src/nrf52/wifi-nrf52.cpp

@@ -0,0 +1,13 @@
+#include "meshwifi/meshhttp.h"
+#include "meshwifi/meshwifi.h"
+
+void initWifi() {}
+
+void deinitWifi() {}
+
+bool isWifiAvailable()
+{
+    return false;
+}
+
+void handleWebResponse() {}