[WIP-Experimental]Onboard qwen1.5-moe-a2.7b model in MaxText

[YixuanWang-99]

Description

Experimental attempt to onboard qwen1.5-moe-a2.7b .
Code is NOT cleaned up yet.

Tests

After the Jax implementation, ckpt conversion, we run the logit_forward_pass_checker.py to test the end to end model deployment. Test on TPU v4.

Checklist

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• I have performed a self-review of my code. For an optional AI review, add the gemini-review label.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run end-to-end tests tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.