MDEV-32618 new auth plugin

PARSEC: Password Authentication using Response Signed with Elliptic Curve

new authentication plugin that uses salted passwords,
key derivation, extensible password storage format,
and both server- and client-side scrambles.

It signs the response with ed25519, but it uses stock
unmodified ed25519 as provided by OpenSSL/WolfSSL/GnuTLS.

Edited by: Sergei Golubchik

mysql-test/suite/plugins/r/parsec.result

@@ -0,0 +1,32 @@
+install soname 'auth_parsec';
+create user test1@'%' identified via parsec using 'pwd';
+ERROR HY000: Operation CREATE USER failed for 'test1'@'%'
+create user test1@'%' identified via parsec using PASSWORD('pwd');
+show grants for test1@'%';
+Grants for test1@%
+GRANT USAGE ON *.* TO `test1`@`%` IDENTIFIED VIA parsec USING 'P0:salt:password'
+connect con1, localhost, test1, pwd;
+select 1, USER(), CURRENT_USER();
+1	USER()	CURRENT_USER()
+1	test1@localhost	test1@%
+disconnect con1;
+connect con2, localhost, test1, pwd;
+select 2, USER(), CURRENT_USER();
+2	USER()	CURRENT_USER()
+2	test1@localhost	test1@%
+disconnect con2;
+connect(localhost,test1,wrong_pwd,test,MASTER_MYPORT,MASTER_MYSOCK);
+connect con3, localhost, test1, wrong_pwd;
+ERROR 28000: Access denied for user 'test1'@'localhost' (using password: NO)
+connection default;
+create function have_ssl() returns char(3)
+return (select if(variable_value > '','yes','no') as 'have_ssl'
+  from information_schema.session_status
+where variable_name='ssl_cipher');
+grant execute on test.* to test1@'%';
+# mysql -utest1 -ppwd --ssl-verify-server-cert -e "select test.have_ssl()"
+test.have_ssl()
+yes
+drop function have_ssl;
+drop user test1@'%';
+uninstall soname 'auth_parsec';