Add a script to generate RDM PID proto from PARAMETER_DESCRIPTION messages

[peternewman]

To simplify adding support for new manufacturer PIDs.

[peternewman]

This should also handle, or probably just be based on, the model collector data.

[peternewman]

Model collector data was covered here:
#240

[peternewman]

This would allow an end user to potentially use a new PID directly without needing the RDM website loop.

[peternewman]

This could generate an overrides.proto file for their use.