AP_DDS: Add UDP support for ChibiOS using the LWIP stack

[Ryanf55]

Feature request

Is your feature request related to a problem? Please describe.

You can only connect real hardware to a companion computer over serial, which is slow.

Describe the solution you'd like

Allow using the new network stack to connect to the companion computer over network, which is much faster

Platform [ x] All

More info

Here's the interface that we already met for the UDP in AP_DDS: https://github.com/eProsima/Micro-XRCE-DDS-Client/blob/master/include/uxr/client/profile/transport/custom/custom_transport.h

It was implemented here: https://github.com/ArduPilot/ardupilot/blob/5bd5aa87a728ebae468e3c3247467d8971a5d6fa/libraries/AP_DDS/AP_DDS_UDP.cpp#L12

As far as I can tell, the ArduPilot DDS over UDP is implemented as a UDP Client on Port 2019. No multicast is used right now. We currently hard code the address to 127.0.0.1 , so it only works in SITL. This is the address for the server address for the DDS agent on the companion computer. It needs to be exposed through a parameter. https://github.com/ArduPilot/ardupilot/blob/5bd5aa87a728ebae468e3c3247467d8971a5d6fa/libraries/AP_DDS/AP_DDS_Client.h#L140

The port is already has a parameter: https://github.com/ArduPilot/ardupilot/blob/5bd5aa87a728ebae468e3c3247467d8971a5d6fa/libraries/AP_DDS/AP_DDS_Client.cpp#L63

[Ryanf55]

This should work. Ready to validate on hardware now.

[Ryanf55]

It's part of 4.5 now.