Fix extended minimal builds with the Core ML EP (#29387)
### Description
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Enables `GetModel()` in extended minimal builds.
### Motivation and Context
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- If it fixes an open issue, please link to the issue here. -->
Fixes https://github.com/microsoft/onnxruntime/issues/29386/. Extended
minimal builds with the Core ML Execution Provider fail because getting
the model metadata in coreml_execution_provider.cc on L63 requires
Graph::GetModel(), which is only available in full (non-minimal) builds.
