Add interface for log messages

[jwulf]

To enable intellisense on custom loggers, add an interface definition for the log messages they will receive.

It looks like:

{
  timestamp: new Date(),
  context: `${frame.getFileName()}:${frame.getLineNumber()}`,
  id: this.id,
  level,
  message,
  time: dayjs().format('YYYY MMM-DD HH:mm:ssA'),
}

[jwulf]

Also, add a link to the totally sweet custom logging implementation in the Zeebe GitHub Action.