coreml - Wrap Core ML execute and forward calls in autorelease pool (#95384)
Summary:
When performing inference using the Core ML delegate, memory is increasing indefinitely. This is due to Core ML allocating memory within `predictionFromFeatures:error:`. Seems that the autorelease pool does not release the return values from the prediction method until inference is stopped completely. So we need to release with `autoreleasepool` manually ([per Apple guidance in the Apple Developer Forums](https://developer.apple.com/forums/thread/692425)).
This commit wraps `autoreleasepool` around the `execute` function of `PTMCoreMLBackend`, which is the scope of where the return values of `predictionFromFeatures:error:` are. Also added in `PTMCoreMLExecutor` for good measure.
Differential Revision: D43520767
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95384
Approved by: https://github.com/mcr229
