Generated state model class seems to go against the NGXS style guide / recommendations #8

Firstly, thanks to all involved on your wonderful work on NGXS!

The generated code (from this CLI) contains a class for the state model, which seems to go against the NGXS style guide / recommendations (ref: https://www.ngxs.io/recipes/style-guide#avoid-saving-class-based-instances-in-your-state) which suggest that interfaces (and thus plain JS objects) should be used.

Just wondering if this is intentional, or just something that needs tweaking in the CLI? Let me know and I'd be happy to submit a PR to make the change.