lib/rsa: allow matching pkcs11 path by object id

lib/rsa: allow matching pkcs11 path by object id

The object= part matches against the label that the pkcs11 token uses
for that object, but in some cases, specifically with a Yubikey using
ykcs11, where the keys have been imported, the labels differ between the
private and public keys [1], making the object= matching useless. These
keys will have the same id however, so matching against that works for
both the private and public part.

[1]: https://github.com/Yubico/yubico-piv-tool/blob/master/doc/YKCS11/Functions_and_values.adoc#key-alias-per-slot-and-object-type

Signed-off-by: Tobias Olausson <tobias@eub.se>