Several of the attribute values defined for use by attribute certificates
use multi-valued data in an ASN.1 SEQUENCE. Allow reading of these values
from a configuration file, similar to how generic X.509 extensions are
handled.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15857)