[Pitch] CharacterSet.contains(Swift.Character) instead of Unicode.Schalar

Evolution Pitches
1

For example:

newlines.contains("\r\n")
"\r\n" is a single character in Swift, and is a newline character on Windows

currentPlatformNewlines.contains("\r\n") == true on Windws
currentPlatformNewlines.contains("\r\n") == false on other platforms