feat(core): move normalize and restore line break functionality to Keyman Core

PR #10697 added functionality to the Keyman for Windows engine to detect the type of line feed being used CRLF, LF, or just CR and normalized it to just LF (u+000A). It then restored the line break used when outputting to the application. This functionality go could be used in the Core and then all the platforms would not need to handle it. It could then be removed from the Windows engine also.