Add MoleculeGPT

[xnuohz]

Issue

• [Community Sprint] GNNs<>LLMs 🚀  #9694
• MoleculeGPT: Dataset+Model+Unit tests+Example #9698

Feature Summary

• Add MoleculeGPTDataset
• Add MoleculeGPT as GNN & LLM Co-training model to PyG
• Add an example for training and testing
• Split the PR into 3 sub-PRs (MoleculeGPT (1/n) - Add dataset #9723, MoleculeGPT (2/n) - Add model #9724, MoleculeGPT (3/n) - Add example #9725)
• Limited hardware resources, can't load lmsys/vicuna-7b-v1.5, use TinyLlama/TinyLlama-1.1B-Chat-v0.1 instead, and the full training pipeline was not tested

[rusty1s]

@xnuohz Looks great. Can you do us a favor and split the PR into multiple? I would imagine we can merge dataset, model and example separately to ease reviewing.

[xnuohz]

@xnuohz Looks great. Can you do us a favor and split the PR into multiple? I would imagine we can merge dataset, model and example separately to ease reviewing.

@rusty1s Got it. I'll do this later.

[puririshi98]

@xnuohz, notice CI fails because:
"E ModuleNotFoundError: No module named 'transformers'"
you need to add "@withPackage('transformers', 'sentencepiece', 'accelerate')"
Since the PyG github CI does not have these installed by default please manually test the unit test and share the results as a comment so we know everything works fine. At NVIDIA we do have CI that tests with these packages installed so once your work is merged it will be mantained :)

[xnuohz]

@puririshi98 Fixed CI and test the unit test locally.

[puririshi98]

LGTM

[puririshi98]

will wait for @rusty1s and @akihironitta to review/merge