migrate expo-router to expo/expo (#23725)

# Why

Migrate expo-router to expo/expo from expo/router so we can version it
with the Expo SDK. Also required for further integration with Expo CLI,
ex

migrate expo-router to expo/expo (#23725)

# Why

Migrate expo-router to expo/expo from expo/router so we can version it
with the Expo SDK. Also required for further integration with Expo CLI,
expo-font, expo-image, etc.

# How

- Migrate `expo-router`, and `@expo/metro-runtime`.
- Fold `expo-head` into `expo-router`.
- Integrate in `apps/sandbox` for low-stakes testing. Another PR can
pull in.

# Test Plan

- `apps/sandbox` starts on all platforms and pulls from expo-router in
the `packages` directory.
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# Checklist

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

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Co-authored-by: Expo Bot <[email protected]>

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