OPC-UA: Disable by config endpoint discovery

Some real world devices like the https://iqunet.com/server-and-data/ includes as the OPC-UA server the FreeOPCUA server running inside a docker. When you discover the endpoints, the IPs advertised are the internal ones in the docker container, so you can not access these endpoint from the network.

It is an issue in the device, but for those cases, just using directly the public IP in which the OPC-UA server is listening as the endpoint is the only solution.

For PLC4x to work in those cases, a config option must be available to disable the endpoint discovering and just connect to the endpoint build with the public IP.