Adding tutorial content for "Train a Large Language Model (LLM) using TPUs on GKE with JAX"

Propose to adding content (Scripts and training code files) for the tutorial [Train a Large Language Model (LLM) using TPUs on GKE with JAX](https://docs.google.com/document/d/1Tl79ct-KWPgdytWCSIsR_Q_ZDDdjZCTjUbQVSckhDrs/edit?resourcekey=0-oIOsGt08A0ZCXwkx7DTDZw&tab=t.0#heading=h.39htcwzd6s73),

The changes have been validated and tested on GKE for both standard and autopilot clusters.

CL for the current draft tutorial: https://critique.corp.google.com/cl/855858604