tests: PUBLICKEY_ACCEPTED_TYPES are effective

Verify the PUBLICKEY_ACCEPTED_TYPES option is handled correctly
and affects the signature algorithm selection based on the
extensions and can be used to limit list of offered mechanisms
to the server.

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit 594c62d718)

include/libssh/pki_priv.h

@@ -47,6 +47,8 @@ int pki_key_ecdsa_nid_from_name(const char *name);
 const char *pki_key_ecdsa_nid_to_name(int nid);
 const char *ssh_key_signature_to_char(enum ssh_keytypes_e type,
                                       enum ssh_digest_e hash_type);
+enum ssh_digest_e ssh_key_type_to_hash(ssh_session session,
+                                       enum ssh_keytypes_e type);
 
 /* SSH Key Functions */
 ssh_key pki_key_dup(const ssh_key key, int demote);