[ORT] Extend reshape fusion (#29027)
Enable reshape fusion for models with symbolic (dynamic) dimensions,
covering patterns found in MobileNetV2, vision encoders, and SLMs.
Changes:
- Match_Shape: allow dimension matching by symbolic dim_param, not just
static values. Needed for SLMs (e.g. Qwen) where `position_ids` takes
`Shape` from `input_ids` — same `dim_param` names, no static values.
- Match_Shape: allow matching when only the gathered dimension agrees
between `Shape` source and reshape root. Needed for vision encoders
(e.g. moondream2) where `Shape` is taken from pre-projection tensor but
`Reshape` operates on post-projection output.
- Match_Shape: add `GlobalAveragePool` passthrough — accept `Shape` from
pre-pool input when gathering batch dim. Needed for MobileNetV2.
- ReshapeHelper: handle zero-dim shapes (`allow_zero=true`) by computing
unknown dim from non-zero dimension product only. Needed for MobileNetV2
reshape fusion output.
- Add corresponding unit tests.
