SignedDataVerifier accepts stale OCSP GOOD responses and can bypass certificate revocation checks

Summary

SignedDataVerifier attempts to perform online revocation checking when enable_online_checks=True, but its OCSP validation logic accepts stale GOOD responses as valid indefinitely. In appstoreserverlibrary/signed_data_verifier.py, _ChainVerifier.check_ocsp_status() verifies the OCSP response signature and CertID match, but never validates the freshness window carried by producedAt, thisUpdate, or nextUpdate.

As a result, a previously valid signed OCSP GOOD response can be replayed after it is expired, and the library will still treat the certificate as good. If an App Store signing certificate or intermediate is ever revoked, applications using this library with online checks enabled can continue accepting JWS objects signed with the revoked key as long as a stale signed OCSP response is replayed.