Add opt-in post-SiLU clipping to MoE operators (#33954)
### Description
Add opt-in `swiglu_limit_after_activation` to MoE/QMoE for models that
clip the gate after SiLU. Existing clipping behavior remains the
default.
The change covers supported floating, integer and block-FP8 CUDA paths,
rejects unsupported combinations explicitly, and adds
numerical/default-behavior tests and operator documentation.
Validation: 18 clipping tests / 55 subtests passed; the full FP8 suite
passed 63 tests / 66 subtests with one existing opt-in memory skip.
Forced dense, GEMV and WMMA cases were verified with CUDA kernel traces.
### Motivation and Context
Ling-3.0-flash-VL requires post-SiLU clipping rather than the existing
pre-SiLU order.
Stacked on microsoft/onnxruntime#33817. This PR adds only the clipping
follow-up and its tests.
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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: a32500b6-be93-4206-a257-11406b00a3f3
