Anonymous logging

dnsproxy will report client IP addresses of failed TLS connections and other network errors. Would you consider a PR for a `--anon-logging` flag to disable all logging that may expose sensitive info? I'd be happy to submit such a PR, but I understand if this isn't something that would be considered.

No files, tests, or entry points are named. Start by tracing the logging paths for failed TLS connections and other network errors, then determine the full set of messages that may expose client or other sensitive information. Done means the proposed flag's scope is defined and those messages are suppressed when it is enabled.

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