AP_DDS: Update Dockerfile to allow --enable-dds build flag

[PQuill33]

Currently, the ArduPilot Dockerfile that is used to build the code does not allow the --enable-dds flag due to a missing dependency in the docker container.

I would like to add an update to the Dockerfile in the ardupilot repo to install the Micro-XRCE-DDS-GEN dependency so that the constructed docker container can build ardupilot with the --enable-dds flag.

Solution Add instructions to clone and install the Micro-XRCE-DDS-GEN repository within the ArduPilot Dockerfile

Alternative Solutions Update the install-prereqs-ubuntu.sh script (or make a copy for use only in the docker container) to handle the installation.

Platform [ X ] All [ ] AntennaTracker [ ] Copter [ ] Plane [ ] Rover [ ] Submarine

Additional context The Dockerfile additions would be similar to the installation instructions found in here. Screenshot shown below.

[PQuill33]

Here's the associated PR with the proposed solution. #28349