CMS_add0_cert: if cert already present, do not throw error but ignore it

CMS_add0_cert: if cert already present, do not throw error but ignore it

Also add checks on failing cert/CRL up_ref calls; improve coding style.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
(Merged from https://github.com/openssl/openssl/pull/19199)