MDEV-32101 CREATE PACKAGE [BODY] for sql_mode=DEFAULT

This patch adds PACKAGE support with SQL/PSM dialect for sql_mode=DEFAULT:

- CREATE PACKAGE
- DROP PACKAGE
- CREATE PACKAGE BODY
- DROP PACKAGE BODY
- Package function and procedure invocation from outside of the package:
    -- using two step identifiers
    SELECT pkg.f1();
    CALL pkg.p1()

    -- using three step identifiers
    SELECT db.pkg.f1();
    CALL db.pkg.p1();

This is a non-standard MariaDB extension.

However, later this code can be used to implement
the SQL Standard and DB2 dialects of CREATE MODULE.

mysql-test/main/sp-package.result

@@ -0,0 +1,51 @@
+SET sql_mode='';
+CREATE OR REPLACE PACKAGE pkg
+PROCEDURE p1();
+FUNCTION f1() RETURNS INT;
+END;
+$$
+CREATE OR REPLACE PACKAGE BODY pkg
+-- variable declarations
+DECLARE a INT DEFAULT 11;
+DECLARE b INT DEFAULT 10;
+-- routine declarations
+PROCEDURE p1()
+BEGIN
+SELECT CURRENT_USER;
+END;
+FUNCTION f1() RETURNS INT
+BEGIN
+RETURN a;
+END;
+-- initialization section
+SET a=a-b;
+END;
+$$
+SHOW CREATE PACKAGE pkg;
+Package	sql_mode	Create Package	character_set_client	collation_connection	Database Collation
+pkg		CREATE DEFINER=`root`@`localhost` PACKAGE `pkg` PROCEDURE p1();
+FUNCTION f1() RETURNS INT;
+END	latin1	latin1_swedish_ci	latin1_swedish_ci
+SHOW CREATE PACKAGE BODY pkg;
+Package body	sql_mode	Create Package Body	character_set_client	collation_connection	Database Collation
+pkg		CREATE DEFINER=`root`@`localhost` PACKAGE BODY `pkg` DECLARE a INT DEFAULT 11;
+DECLARE b INT DEFAULT 10;
+-- routine declarations
+PROCEDURE p1()
+BEGIN
+SELECT CURRENT_USER;
+END;
+FUNCTION f1() RETURNS INT
+BEGIN
+RETURN a;
+END;
+-- initialization section
+SET a=a-b;
+END	latin1	latin1_swedish_ci	latin1_swedish_ci
+CALL pkg.p1();
+CURRENT_USER
+root@localhost
+SELECT pkg.f1();
+pkg.f1()
+1
+DROP PACKAGE pkg;