[codex] Improve authdb table tests

[grahamgilbert]

Summary

• add error coverage for authdb rule-name and rule parsing helpers
• verify constraint filtering ignores non-name and non-equality constraints
• verify getRules propagates security command failures
• assert rule arrays are rendered in table output

Validation

• GOCACHE=/tmp/osquery-extension-go-cache go test ./tables/authdb
• GOCACHE=/tmp/osquery-extension-go-cache go test ./...