implement kernel message logging system

[wjhun]

The use of msg_err, msg_debug, msg_warn, etc. is just a way to deliver crude system messages directly to the console. We could use a logging facility that allows vectoring of messages between the console, a persistent log file, or a socket. It might not be a bad idea to figure out how these log entries might exist in a tuplified version, where things like time, debug level, subsystem, etc., are stored as attributes.

This will require some thinking through and discussion before coding.

[francescolavra]

#1686

[francescolavra]

With #2079, the msg_*() macros print console messages based on their log level and the kernel's configured logging level (err, warn, info). Supported consoles in the kernel core are "serial" (the serial port), "vga" (text output on VGA display), and "net" (raw UDP packets); in addition, the following klibs implements a console driver:

• syslog: sends logs to a syslog server and/or to a local file (with file rotation capabilities)
• gcp: sends logs to the Google Cloud logging server
• cloudwatch: sends logs to AWS CloudWatch