[exupdates][ios] Clean up and rename code signing classes (#21600)

# Why

part 1 of a series of PRs to rename the classes in this module to be
more swift-y as requested by @douglowder. Doing the

[exupdates][ios] Clean up and rename code signing classes (#21600)

# Why

part 1 of a series of PRs to rename the classes in this module to be
more swift-y as requested by @douglowder. Doing the renames in chunks to
make review easier.

# How

Rename, fix lint.

# Test Plan

Build.

# 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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[expo-update][ios] Rename swift classes for correct versioning behavior (#17112)