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.test

@@ -0,0 +1,46 @@
+#
+# CREATE PACKAGE for sql_mode='';
+# Resebmles SQL Standard 'CREATE MODULE'.
+#
+
+SET sql_mode='';
+
+DELIMITER $$;
+CREATE OR REPLACE PACKAGE pkg
+  PROCEDURE p1();
+  FUNCTION f1() RETURNS INT;
+END;
+$$
+DELIMITER ;$$
+
+
+DELIMITER $$;
+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;
+$$
+DELIMITER ;$$
+
+
+SHOW CREATE PACKAGE pkg;
+SHOW CREATE PACKAGE BODY pkg;
+
+CALL pkg.p1();
+SELECT pkg.f1();
+
+DROP PACKAGE pkg;