…lling Model.upload_*

Goal: make it easier for the calling functions to ask for the latest framework version.
It turns out that the current approach complicates calling the upload_* functions, because there is no values of the *_version parameter that mean "latest version".
This leads to the need to have different code paths depending on whether the user has given an explicit version value.
Example of the problem:

```python
def my_import_xgboost_model(
    model_path: str,
    xgboost_version: Optional[str] = None,
):
    if xgboost_version:
            aiplatfor.Model.upload_xgboost_model(model_path=model_path, xgboost_version=xgboost_version)
    else:
            aiplatfor.Model.upload_xgboost_model(model_path=model_path)
```

With this small change, the call is simplified:

```python
def my_import_xgboost_model(
    model_path: str,
    xgboost_version: Optional[str] = None,
):
    aiplatfor.Model.upload_xgboost_model(model_path=model_path, xgboost_version=xgboost_version)
```

P.S. It would be great if the `get_prebuilt_prediction_container_uri` function supported the "latest version" feature.