webpack: Generalize debug-require-webpack-plugin interface.

Now the caller simply imports the debug ‘require’ function as a
module, deciding for itself how to expose it and with what name (in
our case, we expose it as ‘require’ with expose-loader).  Also, remove
a stray console.log.

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

tools/debug-require.js

@@ -0,0 +1,11 @@
+/* global __webpack_require__ */
+
+function debugRequire(request) {
+    return __webpack_require__(debugRequire.ids[request]);
+}
+
+debugRequire.initialize = function (ids) {
+    debugRequire.ids = ids;
+};
+
+module.exports = debugRequire;