Add GPT-OSS model code and config [1/N]

[WoosukKwon]

Add model code and config only. Need to add the MXFP4 MoE support for functionality.

[github-actions]

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[gemini-code-assist]

Code Review

This pull request adds support for the GPT-OSS model, including its implementation, configuration, and registration in various registries. The model implementation appears to be a Mixture-of-Experts architecture. My review has identified a critical issue with device handling during weight loading and a high-severity issue with logging practices, both within the new vllm/model_executor/models/gpt_oss.py file.

[gemini-code-assist]

The hardcoded weight.cuda() call inside the weight loading loop is problematic. It prevents the model from running on non-CUDA devices (e.g., for testing on CPU) and is inefficient as it moves weights to the GPU one by one. This can lead to performance issues and portability problems. The weight loading pipeline should handle device placement, and this line should be removed. The FIXME comment suggests this might be temporary, but it's a critical issue to address before merging.