Add PrivateKeyRaw and PublicKeyRaw support to evp_test

Previously private and public keys had to be pem encoded to be read by
evp_test. This enables us to embed the raw private/public key values
in the test file. The algorithm has to support EVP_PKEY_new_private_key()
and EVP_PKEY_new_public_key() for this to work.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5520)