TestFoundation: use bridging rather than CoreFoundation
TestFoundation: use bridging rather than CoreFoundation

Use bridging to get access to the CoreFoundation results rather than
using the CoreFoundation interfaces.

e78l/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,e78l/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,e78l/swift-corelibs-foundation,e78l/swift-corelibs-foundation,e78l/swift-corelibs-foundation