Add the keyword "nosyslog" to the global "unix" config options. When the user sets "nosyslog" along with "nodaemon" then logs normally sent to syslog are instead printed on stderr.

Also add timestamp to the stderr message to mimic syslog behavior.

This is usefully different from interactive mode. One use case is when used in a container. Container design typically has the application logging to stdout/stderr. The container controlling software (e.g., docker, k8s) look for logs to be on stdout/stderr so it can then
manipulate it (redirect, store, etc). It also has been useful for developing/debugging vpp when interactive mode is not wanted.