test,console: add testing for monkeypatching of console stdio

lib/internal/console/constructor.js contains setters for console._stdout
and console._stderr but these setters are not used in our tests or in
Node.js core. (This is confirmed by our nightly coverage reports.)

Add a test to check monkeypatching _stdout and _stderr on a console
object.

PR-URL: nodejs#26561
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-console-stdio-setters.js

@@ -0,0 +1,20 @@
+'use strict';
+
+// Test that monkeypatching console._stdout and console._stderr works.
+const common = require('../common');
+
+const { Writable } = require('stream');
+const { Console } = require('console');
+
+const streamToNowhere = new Writable({ write: common.mustCall() });
+const anotherStreamToNowhere = new Writable({ write: common.mustCall() });
+const myConsole = new Console(process.stdout);
+
+// Overriding the _stdout and _stderr properties this way is what we are
+// testing. Don't change this to be done via arguments passed to the constructor
+// above.
+myConsole._stdout = streamToNowhere;
+myConsole._stderr = anotherStreamToNowhere;
+
+myConsole.log('fhqwhgads');
+myConsole.error('fhqwhgads');