This diff introduces using of the metadata to provide the `sessionID` by the client for the client authentication in the gRPC `MessagesStream` bidirectional stream.
We are making the following security checks with the `sessionID`:
- Check if the `sessionID` is provided in metadata;
- Check the `sessionID` format validity;
- Check if the `sessionID` exists in the database session table.
Linear task: [[ https://linear.app/comm/issue/ENG-1359/remove-duplication-of-sessionid-in-every-tunnelbroker-message-and-use | ENG-1359 ]]