isIosCppModule function
Returns true when the spec file uses direct C++ specifically for iOS.
Use this instead of isAppleCppModule when deciding whether the iOS Swift
Plugin.swift needs a Registry.register() call — a mixed module with
ios: swift, macos: cpp still needs the iOS Swift registration.
Implementation
bool isIosCppModule(File specFile) =>
PlatformTargetAnalyzer.fromSpec(specFile).supportsIosCpp;