Initial bluetooth_proxy support (#3736)

esphome/components/api/api_connection.cpp

@@ -886,6 +886,9 @@ DeviceInfoResponse APIConnection::device_info(const DeviceInfoRequest &msg) {
 #endif
 #ifdef USE_WEBSERVER
   resp.webserver_port = USE_WEBSERVER_PORT;
+#endif
+#ifdef USE_BLUETOOTH_PROXY
+  resp.has_bluetooth_proxy = true;
 #endif
   return resp;
 }