Improve Support for TypeScript NodeNext/Node16 Module Resolution

[benasher44]

If you update your TypeScript settings to use the new NodeNext moduleResolution setting, you can't use the Docxtemplater class without add an extra .default access:

import Docxtemplater from "docxtemplater";

const d = new Docxtemplater.default();

This problem is explained more generally here.

In Docxtemplater's case, this would likely crash at runtime, since there is no explicit .default property on the export.

This PR uses the recommended guidance to make the types compatible with NodeNext (confirmed still compatible with the previous non-NodeNext/Node16 resolution). It also adds an explicit .default attribute on the export for improved compatibility with those not using the TypeScript esModuleInterop: true setting.

[edi9999]

Thank you !