* Handle discard all logfiles properly
Fixes https://github.com/hashicorp/consul/issues/6892.
The [docs](https://www.consul.io/docs/agent/options.html#_log_rotate_max_files) are stating:
> -log-rotate-max-files - to specify the maximum number of older log
> file archives to keep. Defaults to 0 (no files are ever deleted). Set to
> -1 to disable rotation and discard all log files.
But the `-1` case was not implemented and led to a panic when being
used.
Co-Authored-By: Freddy <freddygv@users.noreply.github.com>
* Added log-file flag to capture Consul logs in a user specified file
* Refactored code.
* Refactored code. Added flags to rotate logs based on bytes and duration
* Added the flags for log file and log rotation on the webpage
* Fixed TestSantize from failing due to the addition of 3 flags
* Introduced changes : mutex, data-dir log writes, rotation logic
* Added test for logfile and updated the default log destination for docs
* Log name now uses UnixNano
* TestLogFile is now uses t.Parallel()
* Removed unnecessary int64Val function
* Updated docs to reflect default log name for log-file
* No longer writes to data-dir and adds .log if the filename has no extension
