repl: support top-level await

Much of the AST visitor code was ported from Chrome DevTools code
written by Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>.

PR-URL: https://github.com/nodejs/node/pull/15566
Fixes: https://github.com/nodejs/node/issues/13209
Refs: https://chromium.googlesource.com/chromium/src/+/e8111c396fef38da6654093433b4be93bed01dce


Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>