Node.js: a shim for overriding "http" and "websocket" modules.

Also added stubs for Server.address()
This was done to prevent crashes in some popular frameworks like express

Supports both CommonJS and the new ES Modules system syntax e.g:

app.js:
const http = require('http')

app.mjs:
import http from "http"

Usage on Node 14.16.x and higher:
{
    "type": "external",
    "processes": {"spare": 0},
    "working_directory": '/project',
    "executable": "/usr/bin/env",
    "arguments": [
        "node",
        "--loader",
        "unit-http/require_shim.mjs"
        "--require",
        "unit-http/require_shim",
        "app.js"
    ]
}

Usage on Node 14.15.x and lower:
{
    "type": "external",
    "processes": {"spare": 0},
    "working_directory": '/project',
    "executable": "/usr/bin/env",
    "arguments": [
        "node",
        "--require",
        "unit-http/require_shim",
        "app.js"
    ]
}

src/nodejs/unit-http/http_server.js

@@ -444,17 +444,30 @@ Server.prototype.setTimeout = function setTimeout(msecs, callback) {
 Server.prototype.listen = function (...args) {
     this.unit.listen();
 
-    const cb = args.pop();
-
-    if (typeof cb === 'function') {
-        this.once('listening', cb);
+    if (typeof args[args.length - 1] === 'function') {
+        this.once('listening', args[args.length - 1]);
     }
 
-    this.emit('listening');
+    /*
+     * Some express.js apps use the returned server object inside the listening
+     * callback, so we timeout the listening event to occur after this function
+     * returns.
+     */
+    setImmediate(function() {
+        this.emit('listening')
+    }.bind(this))
 
     return this;
 };
 
+Server.prototype.address = function () {
+    return  {
+        family: "IPv4",
+        address: "127.0.0.1",
+        port: 80
+    }
+}
+
 Server.prototype.emit_request = function (req, res) {
     if (req._websocket_handshake && this._upgradeListenerCount > 0) {
         this.emit('upgrade', req, req.socket);
@@ -530,7 +543,6 @@ function connectionListener(socket) {
 }
 
 module.exports = {
-    STATUS_CODES: http.STATUS_CODES,
     Server,
     ServerResponse,
     ServerRequest,