[NFR]: Match redacted keys by word parts, and add redact.unmask #67

The redactor masks a key only when the whole key name matches. Keys such as reset_token, access_token, secret_key and db_password show their values unless the developer adds each name to redact.mask. Real config names seldom match one of the default names exactly.

Proposed changes:

• redact.mask and redact.hidden match each word part of a key. The redactor splits a key on _, -, . and camelCase, so token matches reset_token and accessToken.
• An entry with more than one part matches parts that are next to each other. For example, card_number matches cardNumber and customer_card_number.
• A new redact.unmask option, empty by default, fixes false positives such as primary_key. Each entry is a pattern. The pattern must match the whole key, and the match is not case-sensitive. * is the only wildcard. For example, card matches only card, card* also matches card_number, and card also matches customer_card_number.
• hidden comes first, then unmask, then mask. A hidden key is always dropped.
• Update the docs, DebugBarTypes and the changelog. Some values that showed before will now show ***.