Add SSL_get[01]_peer_certificate()

Add SSL_get[01]_peer_certificate()

Deprecate SSL_get_peer_certificte() and replace with
SSL_get1_peer_certificate().
Add SSL_get0_peer_certificate.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/8730)