test: add common.noop, default for common.mustCall()

Export a new common.noop no-operation function for general use.
Allow using common.mustCall() without a fn argument to simplify
test cases.

Replace various non-op functions throughout tests with common.noop

PR-URL: https://github.com/nodejs/node/pull/12027
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

test/parallel/test-console-instance.js

@@ -43,7 +43,7 @@ assert.throws(() => {
 
 // Console constructor should throw if stderr exists but is not writable
 assert.throws(() => {
-  out.write = () => {};
+  out.write = common.noop;
   err.write = undefined;
   new Console(out, err);
 }, /^TypeError: Console expects writable stream instances$/);