NativeCrypto: add CertPath support with PKCS7

Add support for generating CertPath with the
OpenSSLX509CertificateFactory implementation.

This only will encode withrPKCS7 currently. This means it fails the
CertPath serialization test because the serialization and
de-serialization code only uses a provider's default serialization
format. Since this provider is not the default provider and the
default provider uses PkiPath as its default format, the
OpenSSLX509CertPath still fails the tests.

This seems like a problem with the way CertPath is serialized. The
impact of this seems to be that a CertPath implementation must have
"PkiPath" as its default encoding.

Change-Id: Ie0e3577746345108301b02e7a1d4e8ea189f2bda
5 files changed