ConsolePrintStream class

A concrete implementation of PrintStream that writes to the console using stdout.

ConsolePrintStream provides a high-level abstraction over stdout, offering utility methods like write, writeln, newline, flush, and close.

By default, it uses stdout.nonBlocking for efficient, non-blocking output, but you can also provide a custom IOSink to redirect output (e.g., to a file).

📦 Example Usage:

final stream = ConsolePrintStream();
stream.write('Hello');
stream.writeln(' world');
stream.newline();
stream.flush();
await stream.close();

This class is useful when abstracting over console or file output in logging systems, REPLs, shell interfaces, and testable I/O components.