[CoreML] Add Softmax and Split op support (#18358)
### Description
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As title.
### Motivation and Context
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- If it fixes an open issue, please link to the issue here. -->
Added for yolov8 model missing operator support.
https://github.com/microsoft/onnxruntime/issues/17654
Now the model support info looks like:
_CoreMLExecutionProvider::GetCapability, number of partitions supported
by CoreML: 3 number of nodes in the graph: 233 number of nodes supported
by CoreML: 230_
(only missing 3 concat op support due to input 3d shape is not currently
support in CoreML EP Concat).
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Co-authored-by: rachguo <rachguo@rachguos-Mini.attlocal.net>
Co-authored-by: rachguo <rachguo@rachguos-Mac-mini.local>
Co-authored-by: Edward Chen <18449977+edgchen1@users.noreply.github.com>
