crypto/x509: parse additional fields in CertificateRequest

[chauncyc]

What version of Go are you using (go version)?

$ 1.13.4

ParseCertificate parses many common extensions and puts them in the Certificate struct. I'd like for ParseCertificateRequest to do the same. Specifically, I currently manually parse the following fields from CertificateRequest.Extensions, and would like for them to be added to CertificateRequest, with the corresponding changes to ParseCertificateRequest and CreateCertificateRequest, exactly as they're implemented for Certificate:

• KeyUsage
• ExtKeyUsage
• UnknownExtKeyUsage
• IsCA
• MaxPathLen
• BasicConstraintsValid
• MaxPathLenZero
• SubjectKeyId
• PolicyIdentifier

[FiloSottile]

Sounds good, we should even be able to share code with the Certificate parser.

[rsc]

Adding to proposal minutes, seems headed for likely accept.

[rsc]

Based on the discussion above this seems like a likely accept.

[rsc]

No change in consensus, so accepted.