Fix OOB read in InferenceContextImpl::getInputData (#32681)
### Description
`InferenceContextImpl::getInputData` (graph.cc) indexed
`node_.InputDefs()` directly by
the schema input index during shape inference, with no bounds check. Add
the same bounds
check already used by `DataPropagationContextImpl::getInputData` in the
same file, so
`getInputData` returns `nullptr` (treated as "input not available")
instead of indexing
out of bounds.
### Motivation and Context
ONNX schemas can declare trailing inputs as optional (e.g.
`ConvTransposeWithDynamicPads`'s
`Pads`), so a node can validly omit them entirely, shrinking
`Node::InputDefs()` below the
schema's full input count. A `TypeAndShapeInferenceFunction` that
queries such an omitted
optional input's data (e.g. via `ctx.getInputData(index)`) on such a
node reads past the
end of the vector, causing an out-of-bounds read.
