The `test/config-next` CA configs are both updated to use `zlint` to lint TBS
pre-certificates with a throw-away key and treat any lint findings >=
`lints.Pass` as an error, blocking the CA from signing the TBS pre-cert with its
private key.
The CA `issuePrecertificateInner` function is updated to specifically catch
linting related errors from CFSSL to marshal the linting findings to the audit
log. A small unit test for this change is included.
The CA `IssueCertificateForPrecertificate` function remains unchanged: the CFSSL
interface that defines `SignFromPrecert` doesn't facilitate linting. We still
lint final certificates post-issuance with `cert-checker` and accept the
possibility there may be some compliance issues that could occur between the
precertificate passing linting and the final certificate being signed.
Resolves https://github.com/letsencrypt/boulder/issues/4255
eb20b2accd