[WIP] Create hf-gemma-optimum-tpu.libsonnet

[ManfeiBai]

Description

add HF's Gemma model via optimum-tpu

Tests

set up server with gemma-2b/7b and request from client via prompt

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• I have performed a self-review of my code.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run one-shot tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed.

[zpcore]

Why do we uninstall the transformers here?

[zpcore]

Thanks for adding the test. We also need to add the task into the pytorch nightly run job to enable it.