expand shim coverage, additional fs shims, add light stream shim

packages/shim/src/fs/realpath.js

@@ -0,0 +1,12 @@
+export function realpathSync(path) {
+  return typeof path === "string" ? path : String(path);
+}
+
+export function realpath(path, options, callback) {
+  const cb = typeof options === "function" ? options : callback;
+
+  queueMicrotask(() => cb(null, realpathSync(path)));
+}
+
+realpath.native = realpath;
+realpathSync.native = realpathSync;