Llama3.2 vision model AOTI integration

### 🚀 The feature, motivation and pitch Need work to enable: ``` python3 torchchat.py export llama3.2-11B --output-aoti-package-path exportedModels/llama3_2_artifacts.pt2 ``` Features to be added: * Run AOTI export on preprocess, vision encoder and text decoder separately. * This requires dependency on torchtune's exportable modules and perform module transformation needed. * Package them into a single pt2 file. ### Alternatives _No response_ ### Additional context _No response_ ### RFC (Optional) _No response_