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"
    ]
}

test/node/promise_handler/app.js

@@ -1,8 +1,7 @@
-#!/usr/bin/env node
 
 var fs = require('fs');
 
-require('unit-http').createServer(function (req, res) {
+require('http').createServer(function (req, res) {
     res.end();
 
     if (req.headers['x-write-call']) {