Adds option to emit json structured logs

[scottopell]

This introduces two new options that affect logging output, one that turns on json-formatted logs for the log file option and one for the stdout stream.

      --log-json
          Logging to console (ie, stdout) will emit each log record as a json object

          [env: RQBIT_LOG_JSON=]

      --log-file-json
          Log file will contain json-formatted log records

          [env: RQBIT_LOG_FILE_JSON=]

I think I've managed to not change things too much, lmk what you think

[ikatson]

Needs a fix, at least to unbreak the desktop app.

[scottopell]

Thanks for the feedback and pointers, I'm moving this back to a draft for now while I fight with tracing_subscriber

[ikatson]

Also please don't change stderr to stdout for logs. If you really need it for some reason, make it a parameter, but keep the current behavior.

[scottopell]

I'm misunderstanding where the stdout log stream(s) are coming from, I'm seeing duplicated logs, some with human and some with json. I guess need to revisit all the branches of the logging recorder and see what I missed

$ cargo run -- --log-format=json server start /tmp/scratch 2&>/dev/null
2024-10-03T15:55:58.558134Z  INFO rqbit: inreased open file limit limit=61440
{"timestamp":"2024-10-03T15:55:58.558237Z","level":"INFO","fields":{"message":"inreased open file limit","limit":61440},"target":"rqbit"}

[ikatson]

this makes log file contain ANSI escape codes which makes it hard to grep and use. Those escape codes are intended for terminal use only.

PR LGTM otherwise, I'd merge if not for this