Add Certificate error flags support to OpenSSL with CAPI certificate validation

[anrossi]

When deferred certificate validation is used with Schannel, it provides both a set of flags of all certificate validation issues encountered, and an error code for the most severe of those. OpenSSL certificate validation doesn't provide this on Linux or macOS, but on Windows, when CAPI is used to do certificate validation, these flags could be exposed to the application layer.