Allow custom authenticatedAttributes

[dettoni]

Handling inside forge attributes like messageDigest and signingTime is really nice, but not allowing any other attributes is quite limiting.

This change allow the user to build and use any attribute with ASN.1.

This problem have been addressed in #400 but no PR were open. I used the name asn1Value instead of rawValue because I think rawValue would be misleading.

An example of the need for this is in #768 where it is proposed a new attribute signingCertificateV2, but signingCertificateV2 can be way more complex than the version proposed. sigPolicyId is another example of attribute that would be quite hard to implement in a general form but is not hard to build for an specific policy.