Experimental secret search with $secret

What's Changed

• Add secrets search and bump DotUtils.MsBuild.BinlogRedactor.SensitiveDataDetector version by @YuliiaKovalova in #829
• builds that don't have BuildStarted and BuildFinished are considered succeeded, not failed (e.g. for binlogs produced from just the evaluation)

Search for $secret to find potential secrets in the binlog.

Full Changelog: v2.2.376...v2.2.379