Use SSL_get0_peer_signature_name instead of SSL_get_peer_signature_nid

Use SSL_get0_peer_signature_name instead of SSL_get_peer_signature_nid

SSL_get0_peer_signature_name returns a string instead of hardcoded NIDs.
NIDS do not work with provider provided signatures or the new PQ
signatures introduced in OpenSSL 3.5.

Remove also the comment that was added earlier that says that there
is no proper API replacement for SSL_get_peer_signature_nid yet as
OpenSSL 3.5.0 has now introduced it.

Change-Id: I2bc782ceebcc91a8dc8ada0bb72ac042be46cad6
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Antonio Quartulli <antonio@mandelbit.com>
Message-Id: <20250402153337.5262-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31336.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>