[@expo/config] Remove originalFullName currentFullName hack from exported config (#21070)

# Why

This reverts https://github.com/expo/expo-cli/pull/3376 and
https://github.com/expo/expo-cli/pull/

[@expo/config] Remove originalFullName currentFullName hack from exported config (#21070)

# Why

This reverts https://github.com/expo/expo-cli/pull/3376 and
https://github.com/expo/expo-cli/pull/3494.

These were added for AuthSession and Push notification registration.
Neither of these use this anymore:
- AuthSession deprecated use of the proxy use with the field from the
manifest: https://github.com/expo/expo/pull/17327. It supports supplying
them via arguments.
- Push notification prefers `projectId` now:
https://github.com/expo/expo/pull/14265. Also it allows supplying them
via arguments.

These auto config augmentations are causing issues with `eas build`
since the generated full name could differ from the actual full name:
1. Create project in an org on the website.
2. `npx expo init ...`
3. `eas init --id <>`
4. Remove `owner` from manifest.
5. `eas build`
6. Download artifact, inspect embedded config, see that it has the
correct `projectId` yet also a `currentFullName` and `originalFullName`
containing the current logged-in user rather than the actual one
corresponding to the projectId.

# How

One fix we could do here would be to read the projectId and get the
truthful full name, but that adds a network dependency and is probably
not worth it.

So, instead, I decided to just remove the hack since they are no longer
needed in the two libraries this was added for.

# Test Plan

Run all tests.

# Checklist

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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 `expo prebuild` & EAS Build (eg:
updated a module plugin).

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chore(config): drop unused features (#19800)

* chore: drop unused and deprecated functions

- Remove isDynamicFilePath, readConfigJson, findConfigFile, configFilename, readExpRcAsync, resetCustomC

chore(config): drop unused features (#19800)

* chore: drop unused and deprecated functions

- Remove isDynamicFilePath, readConfigJson, findConfigFile, configFilename, readExpRcAsync, resetCustomConfigPaths, setCustomConfigPath, writeConfigJsonAsync, isLegacyImportsEnabled
- Remove getManagedExtensions
- Remove target option from expo/metro-config
- Remove EXPO_TARGET environment variable support

* build

show more ...

chore: migrate config, config-plugins, config-types, prebuild-config (#17958)