onnxruntime

[CoreML EP] Add Flatten Op and LRN Op support (#14857)

### Description
<!-- Describe your changes. -->

As title.

CoreML Spec for reference: 


https://apple.github.io/coremltools/mlmodel/Format/NeuralNetwork.html#flattento2dlayerparams


https://apple.github.io/coremltools/mlmodel/Format/NeuralNetwork.html#lrnlayerparams

### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->

Fill CoreML Clipchamp usage gaps.

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Co-authored-by: rachguo <rachguo@rachguos-Mini.attlocal.net>