Write protobuf files to generate message structures to pass data between functions

Description

We want to replace our current JSON message structures with protobuf messages. Write .proto files to replicate data transfer from current JSON format.

Further details

Message structure should be explicitly major versioned - could use example as in https://gitlab.developers.cam.ac.uk/uis/devops/experiments/mk2155/protobuf-prototype

Task list

• Write proto files to match current, under proto directory.

Acceptance criteria

• Proto files exist for message formats

Links/references