Use node name to uniquify the subgraph nodes. (#15855)
### Description
<!-- Describe your changes. -->
Use the unique name of the function node name to uniquify the subgraph
node names.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
Prevent duplicate node names in the graph.
- If it fixes an open issue, please link to the issue here. -->
https://github.com/microsoft/onnxruntime/issues/15849
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Co-authored-by: Satya Jandhyala <sajandhy@microsoft.com>
