Make /_config/*.jst use ES6 superclass calls, fix failure to await the superclass...

Make /_config/*.jst use ES6 superclass calls, fix failure to await the superclass calls, use (await import('@ndcode/jst_server')).default rather than the _jst_server builtin variable provided by jst (because npm now uses a flat node_modules structure, so there is no risk of loading a second copy of jst_server module)