Parse crlEntryExtensions in CRLs

[magnuswatn]

Not sure if this was an oversight, or done on purpose, but extensions in RevocationListEntries were not being parsed. Now they get parsed.

Before change:

❯ step crl inspect --insecure 'http://crl4.digicert.com/sha2-ev-server-g1.crl' | grep "Revoked Certificates:" -A 5
        Revoked Certificates:
            Serial Number: 2799225036922445944820450433099856353 (0x021B1C73250B47C4CE8F305E639B79E1)
                Revocation Date: 2023-08-23 10:43:00 +0000 UTC
            Serial Number: 14874532436251617487517665762619838282 (0x0B30BB11F55A7DF580DDC276AF324F4A)
                Revocation Date: 2023-11-23 12:19:17 +0000 UTC
            Serial Number: 21201432819745242598424189347483327802 (0x0FF33F57C756BC0BA8A6B78606179D3A)

After change:

❯ ./bin/step crl inspect --insecure 'http://crl4.digicert.com/sha2-ev-server-g1.crl' | grep "Revoked Certificates:" -A 5
        Revoked Certificates:
            Serial Number: 2799225036922445944820450433099856353 (0x021B1C73250B47C4CE8F305E639B79E1)
                Revocation Date: 2023-08-23 10:43:00 +0000 UTC
                CRL Entry Extensions:
                    X509v3 CRL Reason Code:
                        Key Compromise

[hslatman]

Thank you, @magnuswatn! I believe this to be an oversight. Change looks good, so I'll merge it. Pinging @maraino so that he at least sees it too 🙂