Qualified data types in SP

Under terms of MDEV-19632 we're introducing qualified data types, e.g.:

SET sql_mode=ORACLE;

CREATE TABLE t1 (a mariadb_schema.DATE);

This syntax is needed for disambiguation.

In stored routines this syntax is not needed for disambiguation, because sql_mode is stored together with the SP definition, so data types are unambiguously parsed according to the SP sql_mode.

Anyway, for symmetry purposes, let's add qualified syntax inside SP definitions, to make qualified types work in:

• Function return type

  SET sql_mode=ORACLE;

  DELIMITER $$

  CREATE FUNCTION f1() RETURN mariadb_schema.DATE AS

  BEGIN

  RETURN CURRENT_DATE;

  END;

  $$

  DELIMITER ;

• Parameter type

  SET sql_mode=ORACLE;

  DELIMITER $$

  CREATE PROCEDURE p1(a mariadb_schema.DATE) AS

  BEGIN

  NULL;

  END;

  $$

  DELIMITER ;

• Local variable type

  SET sql_mode=ORACLE;

  DELIMITER $$

  CREATE PROCEDURE p1() AS

  a mariadb_schema.DATE;

  BEGIN

  NULL;

  END;

  $$

  DELIMITER ;