log: errors should include hints to the operator with remediation steps

[dhartunian]

Currently, error log messages typically omit remediation steps and customers have to resort to either searching documentation or forums to understand what to do when they see something. In addition, some "error" level messages require no remediation at all and simply offer a notification that something out of the ordinary happened that the DB is able to safely recover from.

The desired feature here is an API that can nudge log message writers to provide remediation along with their error message.

Jira issue: CRDB-15470