* Add craft-pkcs7: DER, X.509, CMS SignedData, PKCS #12, RFC 3161 and revocation from PdfCraft
Moved from PdfCraft's crates/sign at 1d7a9f9f: der, x509, cms, pkcs12, timestamp,
revocation, keys, rsa_pad and ec512, with their unit tests, the integration tests
that need no PDF, and the test keys.
x509 no longer returns PdfCraft's worded sentences: signing_problem gives a
SigningProblem and build_chain_noted a Refused (reason and the two certificates).
The checks behind them are unchanged. Error is SignError without its PDF variants.
* craft-pkcs7: write the certificate serial verbatim in SignerInfo and ESSCertIDv2
A serial with its high bit set and no leading zero was written with one added, so
the signer identifier and the signing-certificate attribute named a different
number than the certificate has.
Ported from storytold/pdfcraft#6868. The test uses a certificate that really has
such a serial and also checks that the signer's certificate is found.
* craft-pkcs7: note why RIPEMD-160 is supported
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Co-authored-by: jonathanwxh-cell <jonathanwxh@gmail.com>
