TGTalker as example of LLM for temporal graph data in TGM

[shenyangHuang]

Description
Implement the TGTalker LLM framework in TGM, based on "Are Large Language Models Good Temporal Graph Learners?" paper.

Motivation
TGTalker is the first to provide textual explanability on temporal graph and doesn't require fine-tuning LLM. This can be adapted to any datasets in TGM as well as any custom dataset.

Additional context
providing an example for link prediction

[Jacob-Chmura]

@shenyangHuang Moving to beta release 3, as we had discussed potentially letting this stream of work be taken up via course project for network science.