Test importing spki and pkcs8 keys with algorithm-specific OIDs

We should test importing RSA keys with OID `id-RSASSA-PSS` or `id-RSAES-OAEP`, and ECDH keys with OID `id-ecDH`; both well-formed and malformed cases (e.g. RSA keys with these OIDs with missing or malformed paramers, as in #297).