util/log: automatic log redaction

[jseldess]

PR: cockroachdb/cockroach#48051

From release notes:

The server CLI commands (start, start-single-node, demo) now support a new flag named --redactable-logs, which introduces markers in generated log entries to facilitate redaction of sensitive information by cockroach debug zip and other CockroachDB APIs. This is an experimental feature currently not enabled by default, but is recommended for all deployments and will be enabled by default in a later version. Note: the flag is advertised (in --help) by cockroach start and cockroach start-single-node, where log files are expected as a matter of course; it is also supported, yet hidden (from --help), by every other CLI command because every command can also produce log entries when passed --log-dir or --logtostderr. [#48051][#48051] {% comment %}doc{% endcomment %}

[jseldess]

Dup of #7866