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.

sql/sp.cc

@@ -2628,7 +2628,7 @@ Sp_handler::sp_resolve_package_routine(THD *thd,
                                        const Sp_handler **pkg_routine_handler,
                                        Database_qualified_name *pkgname) const
 {
-  if (!thd->db.length || !(thd->variables.sql_mode & MODE_ORACLE))
+  if (!thd->db.length)
     return false;
 
   return name->m_explicit_name ?