This diff introduces handling messages to be sent from the client by [[ https://github.com/CommE2E/comm/blob/38225b76efeea3162464882577dc81ca487a7f03/shared/protos/tunnelbroker.proto#L111 | messagesToSend ]] incoming gRPC message.
Tunnelbroker receives messages from the client and puts them into a messages table in the database, then put a message into the AMQP queue to trigger the delivery. Tunnelbroker generates a unique message ID for each message and sends it back to the client as a [[ https://github.com/CommE2E/comm/blob/38225b76efeea3162464882577dc81ca487a7f03/shared/protos/tunnelbroker.proto#L133 | processedMessages ]].
Linear task: [[ https://linear.app/comm/issue/ENG-2060/implement-tunnelbroker-grpc-messagesstream-api-handler-in-rust | ENG-2060 ]]