repl: fix require('3rdparty') regression
Fix module loading of third-party modules in the REPL by inheriting module.paths from the REPL's parent module.
Commit ee72ee75 ("module,repl: remove repl require() hack") introduced a regression where require() of modules in node_modules directories no longer worked in the REPL (and fortunately only in the REPL.) It turns out we didn't have test coverage for that but we do now.
Fixes: https://github.com/nodejs/node/issues/4208
R=@silverwind?