2020.1 Structured logging improvements

Protocol levels: server/client shows the protocol levels for every release, and the 2020.1 release has the following improvements for structured logging:

• All event types have a version 50, which adds a unique command identifier and the current serverId after the command number field (5th column).
• For commands that result in log events being written on multiple servers, the unique command identifier propagates across the server to allow those events to be matched. Examples include submits from edge servers, replica forwarded commands, remote depot access, and P4AUTH.
• The 11.50 trigger event type has two additional fields:
  • a trigger type of trigger, extension, or bgtask for background task
  • an execution lapse time
• Trigger arguments are now separated by the colon : character to match the command arguments format.
• The serverlog.version.N configurable can be used to pin a structured log file to the format of a specific server version. For example:
  • to retain the 2019.2 structured log events format, set this configurable to 49
  • to retain the format of 2019.1, set this configurable to 48