logging: Add time_local option to use local time instead of UTC

[francislavoie]

Closes #5019

Adds a new time_local flag for encoders which logs in local time.

Example config:

:8881 {
	log {
		format console {
			time_format wall_milli
			time_local
		}
	}
}

Before:

2022/10/02 20:23:38.548	INFO	tls	finished cleaning storage units
2022/10/02 20:23:39.603	info	http.log.access.log0	handled request	{"request": {"remote_ip": "127.0.0.1", "remote_port": "45332", "proto": "HTTP/1.1", "method": "GET", "host": "localhost:8881", "uri": "/", "headers": {"Accept": ["*/*"], "User-Agent": ["curl/7.74.0"]}}, "user_id": "", "duration": 0.000001415, "size": 0, "status": 0, "resp_headers": {"Server": ["Caddy"]}}

After:

2022/10/02 20:23:27.753	INFO	tls	finished cleaning storage units
2022/10/02 16:23:29.178	info	http.log.access.log0	handled request	{"request": {"remote_ip": "127.0.0.1", "remote_port": "45326", "proto": "HTTP/1.1", "method": "GET", "host": "localhost:8881", "uri": "/", "headers": {"User-Agent": ["curl/7.74.0"], "Accept": ["*/*"]}}, "user_id": "", "duration": 0.000001377, "size": 0, "status": 0, "resp_headers": {"Server": ["Caddy"]}}

As you can see the default logger still uses UTC, but the configured access logger uses local time (for me, -4h).

[mholt]

Awesome, that was easier than I thought!

Thanks for the patch. If you have a chance do you want to resolve the conflict and then feel free to merge this in?