* Add code to download model from Hugging Face
 * Fix set_backend that was wrongly placed
 * Update code to compile and execute the export inside the script

* Add code to download model from Hugging Face
* Fix set_backend that was wrongly placed
* Update code to compile and execute the export inside the script

call syntax :
```
python file.py test_case.unit_test
```

- previous call :
```
python aidge_export_cpp/unit_tests/test_export.py test_operator_export.test_export_<operator>_<test_case>
```
- new call :
```
python aidge_export_cpp/unit_tests/test_export.py test_operator_export.<operator>_<test_case>
```