move shim to new package

packages/shim/src/node/net.js

@@ -0,0 +1,19 @@
+function notAvailable(name) {
+  return function () {
+    throw new Error(`net.${name}() is not available in the web version.`);
+  };
+}
+
+export const createServer = notAvailable("createServer");
+export const createConnection = notAvailable("createConnection");
+export const connect = notAvailable("connect");
+export class Socket {
+  constructor() {
+    throw new Error("net.Socket is not available in the web version.");
+  }
+}
+export class Server {
+  constructor() {
+    throw new Error("net.Server is not available in the web version.");
+  }
+}