[Model] Support Grok1

[mgoin]

FIX #3472

Ported from https://github.com/ROCm/vllm/blob/main/vllm/model_executor/models/grok1.py with some missing features added - namely enabling logits_soft_cap, proper scaling, and gelu instead of silu

Evaluation on gsm8k using Grok1 FP8 from https://huggingface.co/amd/grok-1-FP8-KV

lm_eval --model vllm --model_args pretrained=amd/grok-1-FP8-KV,tensor_parallel_size=8 --trust_remote_code --tasks gsm8k --num_fewshot 5 --batch_size auto

vllm (pretrained=amd/grok-1-FP8-KV,tensor_parallel_size=8,trust_remote_code=True), gen_kwargs: (None), limit: None, num_fewshot: 5, batch_size: auto
|Tasks|Version|     Filter     |n-shot|  Metric   |   |Value |   |Stderr|
|-----|------:|----------------|-----:|-----------|---|-----:|---|-----:|
|gsm8k|      3|flexible-extract|     5|exact_match|↑  |0.6073|±  |0.0135|
|     |       |strict-match    |     5|exact_match|↑  |0.5883|±  |0.0136|

Verified that vllm serve amd/grok-1-FP8-KV -pp 8 --trust-remote-code works

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[jeejeelee]

LGTM, also cc @DarkLight1337

[DarkLight1337]

Please update the model registry tests to include this model.