[PlistHelper] Replace deprecated CoreFoundation APIs.
[PlistHelper] Use actual signatures for all CF functions.
[PlistHelper] Refactor importing CF functions.
[PlistHelper] Cleanup function definitions.
[PlistHelper] Re-organize and clean-up more.
[PlistHelper] Re-organize a bit more to reduce namespace noise.
[PlistHelper] Merge and clean-up tests.
[PlistHelper] Make tests green and remove XML fixture.
[PlistHelper] Make rubocop happy.