[ios][image-picker] Add preferredAssetRepresentationMode to image pic…

…ker (#22456)

# Why

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Please describe the motivation for this PR, and link to relevant GitHub issues, forums posts, or feature requests.
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- Resolves #21707
- The issue above is not that copying to cache is slow, but that some videos are transcoded into a more compatible format which is done on the fly and takes a lot of time
- `preferredAssetRepresentationMode` gives us the option to skip transcoding

# How

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How did you build this feature or fix this bug and why?
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- Added a new enum with proper documentation
- Add this new enum as an option in `ImagePickerOptions`
- Handle this in the native side following the code style of the module

# Test Plan

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Please describe how you tested this change and how a reviewer could reproduce your test, especially if this PR does not include automated tests! If possible, please also provide terminal output and/or screenshots demonstrating your test/reproduction.
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- Ran the `bare-expo` app on iOS
- Imported `expo-image-picker` and launched the photo library picker with all the options
- Tested a `.hevc` video with `automatic` and `current`, `current` is much faster

# Checklist

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Please check the appropriate items below if they apply to your diff. This is required for changes to Expo modules.
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- [x] Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
- [x] Conforms with the [Documentation Writing Style Guide](https://github.com/expo/expo/blob/main/guides/Expo%20Documentation%20Writing%20Style%20Guide.md)
- [x] This diff will work correctly for `npx expo prebuild` & EAS Build (eg: updated a module plugin).

packages/expo-image-picker/CHANGELOG.md

@@ -17,6 +17,7 @@
 ### 🎉 New features
 
 - Added ability to choose the camera-facing type. ([#22143](https://github.com/expo/expo/pull/22143) by [@YoussefHenna](https://github.com/YoussefHenna))
+- Added ability to choose the preferred asset representation mode on iOS 14+. ([#22456](https://github.com/expo/expo/pull/22456) by [@thespacemanatee](https://github.com/thespacemanatee))
 
 ### 🐛 Bug fixes