Create UITesting target with:
- AppCommandLine/AppEnvironment: strongly typed refactoring of PP_*
environment values
- AccessibilityInfo: identifies and locates elements for UI testing
Make the app behave differently when launched with `.uiTesting`, and
expose the flag to SwiftUI via `.environment(\.isUITesting)` to:
- Use the mock AppContext
- Skip onboarding
Add PassepartoutUITests target with two screenshot tests:
- Connected screen
- Profile modal
The Library package offers the PassepartoutImplementations target for
OpenVPN/OpenSSL and WireGuard/Go, but it doesn't need it itself. Only
the main app does, so move the dependency there.
On the other side, drop the potentially problematic AppUI meta target.
Move platform filters to the Xcode project.
Indirectly fixes a crash with Xcode 16 Previews on iOS (forced to use
legacy previews before):
https://forums.developer.apple.com/forums/thread/756681
Move Core Data tests out of the Library package so that we can still use
the more efficient `swift test` for most tests.
Create a PassepartoutTests target only for tests that require
`xcodebuild`, like Core Data tests.
Eventually:
- PRs only run SwiftPM tests
- Releases run ALL tests with `scan` before `gym`
