[EP ABI] Update Graph_GetGraphView() implementation

[chilo-ms]

Description

In some cases, e.g. when model has a node that produces output consumed by multiple nodes, calling the current implementation of Graph_GetGraphView() to get a subgraph returns incorrect OrtGraph.

This PR fixes the issue.

• Original graph:

  

• Incorrect graph after calling Graph_GetGraphView() to get the subgraph:

  It includes three of the nodes from the original graph. The topk_indices is the output of the TopK and it shouldn't be added as a graph input shown in the graph below. The API implementation has issue handling this case. If we feed this subgraph into TRT parser, it would fail to parse the graph.

  

• Correct graph after calling Graph_GetGraphView() to get the subgraph:

  It includes three of the nodes from the original graph. The topk_indices now is not added as a graph input. Instead, the topk_indices is added as a graph output which is expected as Mod is in another subgraph that consumes it, so this subgraph has to make topk_indices a graph output.

  

Motivation and Context