onnxruntime

Fix issue in constant-propagation inside function subgraph (#16330)

### Description

The SequenceMap function-op has a graph-attribute. ORT's
constant-folding optimization may identify constant-expressions inside
the subgraph and promote them to constants, stored as initializers in
the main graph. When it does this, the optimization updates the subgraph
to remove the corresponding nodes.

When we expand a SequenceMap node by inlining its function-expansion, we
need to use this updated subgraph. However, the existing code uses the
original graph-attribute (GraphProto), instead of regenerating it from
the modified subgraph. This results in producing a graph with duplicate
definitions for the constant-folded variable, resulting in an error
during graph-resolve.

This PR fixes this issue (just a single line fix), and adds a test-case
to cover this scenario.

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Signed-off-by: Ganesan Ramalingam <grama@microsoft.com>
Co-authored-by: Suryaprakash Shanmugam <suryaprakash.shanmugam@intel.com>