Model does not have a sagemaker_session property

**PySDK Version**
- [ ] PySDK V2 (2.x)
- [ X] PySDK V3 (3.x)

**Describe the bug**
A clear and concise description of what the bug is.

ModelStep expects the Model class to have a `sagemaker_session` attribute but the spec does not allow it

**To reproduce**

Provide a Model instance as the `model` argument of the register model step arguments

**Expected behavior**
ModelStep can be instantiated with a repack step

**Screenshots or logs**
If applicable, add screenshots or logs to help explain your problem.

**System information**
A description of your system. Please provide:
- **SageMaker Python SDK version**: 3
- **Framework name (eg. PyTorch) or algorithm (eg. KMeans)**: SKLearn
- **Framework version**: 1.4.2
- **Python version**: 3.11
- **CPU or GPU**: CPU
- **Custom Docker image (Y/N)**: N

**Additional context**
Add any other context about the problem here.

首先定位 ModelStep、Model 类，以及所报告复现中涉及的 register model step 参数。检查 repack step 如何访问 model.sagemaker_session，以及模型规范如何处理该属性；当 Model 实例可以通过 repack step 实例化 ModelStep 时，即表示完成。

由索引模型根据 Issue 内容生成。