feat: update GemmaRMSNorm

[zhyncs]

Motivation

Await the review and release of FlashInfer
ref flashinfer-ai/flashinfer#477

Modifications

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.

[zhyncs]

gsm8k
python3 -m sglang.launch_server --model google/gemma-2-2b --disable-radix-cache
python3 benchmark/gsm8k/bench_sglang.py

current

Latency: 15.371
Invalid: 0.005
Accuracy: 0.270

Latency: 15.183
Invalid: 0.000
Accuracy: 0.260

main

Latency: 19.638
Invalid: 0.005
Accuracy: 0.265

Latency: 19.716
Invalid: 0.005
Accuracy: 0.260