vm: add Synthetic modules

- Refactor vm.SourceTextModule (again)
- Add vm.Module abstract superclass
- Add vm.SyntheticModule

Refs: https://heycam.github.io/webidl/#synthetic-module-records

PR-URL: https://github.com/nodejs/node/pull/29864


Reviewed-By: Guy Bedford <guybedford@gmail.com>