💡Allow logging to stdout instead of stderr

[septatrix]

Describe the feature you'd like
I would like for cloudflared to log to stdout instead of stderr

Describe alternatives you've considered
Redirect them manually, however, this is not possible in the container as those do not include any shells which would enable redirection

Additional context
When output is send to stderr many things assume they are errors, like kubernetes or systemd, see last comment of #296