Add syslog logger implementation

[ranma]

This implements RFC5424 version of the protocol.

See #1819

I didn't use https://github.com/arcao/Syslog since the protocol itself is trivial and most of the libraries functionality is not needed here. The library also doesn't support setting the PROCID field, which is set to a random id to indicate a reboot here.

2024-09-15T12:41:21.466816+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] [SyslogLogger] Logging to 192.168.8.240
2024-09-15T12:41:21.466816+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] WiFi got ip: 192.168.8.242
2024-09-15T12:41:21.474350+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Network connected
2024-09-15T12:41:26.618582+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Websocket: [/livedata][1] connect
2024-09-15T12:41:30.963775+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Admin AP remaining seconds: 10 / 180
2024-09-15T12:41:40.977250+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Admin AP remaining seconds: 20 / 180
2024-09-15T12:41:50.985588+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Admin AP remaining seconds: 30 / 180
2024-09-15T12:42:00.999822+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Admin AP remaining seconds: 40 / 180
2024-09-15T12:42:11.007716+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Admin AP remaining seconds: 50 / 180
2024-09-15T12:42:11.575805+02:00 OpenDTU-347AF0 OpenDTU[e4975f6a] Websocket: [/livedata][1] disconnect
[...restarting from web UI, TASKID changes to indicate restart...]
2024-09-15T12:42:18.684665+02:00 OpenDTU-347AF0 OpenDTU[306b82ba] [SyslogLogger] Logging to 192.168.8.240
2024-09-15T12:42:18.684963+02:00 OpenDTU-347AF0 OpenDTU[306b82ba] WiFi got ip: 192.168.8.242
2024-09-15T12:42:18.685450+02:00 OpenDTU-347AF0 OpenDTU[306b82ba] Network connected
2024-09-15T12:42:28.188873+02:00 OpenDTU-347AF0 OpenDTU[306b82ba] Admin AP remaining seconds: 10 / 180
2024-09-15T12:42:38.199718+02:00 OpenDTU-347AF0 OpenDTU[306b82ba] Admin AP remaining seconds: 20 / 180
2024-09-15T12:42:48.210778+02:00 OpenDTU-347AF0 OpenDTU[306b82ba] Admin AP remaining seconds: 30 / 180
2024-09-15T12:42:58.221810+02:00 OpenDTU-347AF0 OpenDTU[306b82ba] Admin AP remaining seconds: 40 / 180

[stefan123t]

@khschmidt in #2278 has successfully built and used this PR to configure his OpenDTU using remote syslog.

@tbnobody would you want to merge this into master or are there some objections from the project side ?

[ranma]

Updated to match the version that was committed into OpenDTU-OnBattery:

[broth-itk]

I am running this patch since 2 weeks now and OpenDTU creates 20MB logs per day (three inverters).
It works very well and the logs are actually quite useful.

[stefan123t]

Adding ESP-IDF Logging framework might be a way to filter log file generation in Serial, Web Console and Syslog #2361