feat: add an --exporter flag to specify which will we use to export the model

As the current qwen3 implementation, use model type to differentiate is very strange because model type should not be different for same model.

Suggest use --exporter to export model by different ways like

- default -> renyi's
- GenAI -> Supreet's
- Mxxx -> xxx

Related https://github.com/microsoft/winml-cli/pull/996