MDEV-31855 validate ssl certificates using client password

if the client enabled --ssl-verify-server-cert, then
the server certificate is verified as follows:

* if --ssl-ca or --ssl-capath were specified, the cert must have
  a proper signature by the specified CA (or CA in the path)
  and the cert's hostname must match the server's hostname.
  If the cert isn't signed or a hostname is wrong - the
  connection is aborted.

* if MARIADB_OPT_TLS_PEER_FP was used and the fingerprint matches,
  the connection is allowed, if it doesn't match - aborted.

* If the connection uses unix socket or named pipes - it's allowed.
  (consistent with server's --require-secure-transport behavior)

otherwise the cert is still in doubt, we don't know if we can trust
it or there's an active MitM in progress.

* If the user has provided no password or the server requested an
  authentication plugin that sends the password in cleartext -
  the connection is aborted.

* Perform the authentication. If the server accepts the password,
  it'll send SHA2(scramble || password hash || cert fingerprint)
  with the OK packet.

* Verify the SHA2 digest, if it matches - the connection is allowed,
  otherwise it's aborted.

mysql-test/lib/generate-ssl-certs.sh

@@ -27,7 +27,7 @@ openssl rsa -in server-key.pem -out server-key.pem
 # sign the server certificate with CA certificate
 openssl ca -keyfile cakey.pem -days 7300 -batch -cert cacert.pem -policy policy_anything -out server-cert.pem -in demoCA/server-req.pem
 
-# server certificate with different validity period (MDEV-7598)
+# server certificate with different validity period (MDEV-16266)
 openssl req -newkey rsa:4096 -keyout server-new-key.pem -out demoCA/server-new-req.pem -days 7301 -nodes -subj '/CN=server-new/C=FI/ST=Helsinki/L=Helsinki/O=MariaDB'
 openssl rsa -in server-new-key.pem -out server-new-key.pem
 openssl ca -keyfile cakey.pem -days 7301 -batch -cert cacert.pem -policy policy_anything -out server-new-cert.pem -in demoCA/server-new-req.pem