console: make dirxml an alias for console.log

This method was previously exposed by V8 (since node 8.0.0) but not
implemented in node.

PR-URL: https://github.com/nodejs/node/pull/17152
Refs: https://github.com/nodejs/node/issues/17128


Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>