GPT-OSS: read the clamped SwiGLU's alpha and limit from the config (#49346)
The experts hardcoded alpha=1.702 and limit=7.0. They become config
attributes with those defaults (GptOssConfig, and OpenAI Privacy Filter's
config built on it), so the value lives where kernels and other expert
implementations can read it instead of repeating the constants.
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>