refactor: avoid unnecessary code and prepare to plugin usage (#3714)

Author: alexander-akait

lib/Server.js

@@ -521,6 +521,38 @@ module.exports = {
 
 - The `sockWrite` public method was renamed to `sendMessage`.
 - The `profile` option was removed in favor [`ProfilingPlugin`](https://webpack.js.org/plugins/profiling-plugin/).
+- The `addDevServerEntrypoints` method was removed in favor of manual configuration.
+
+  v4:
+
+  ```js
+  const webpack = require("webpack");
+  const DevServer = require("webpack-dev-server");
+
+  const config = {
+    entry: [
+      // Runtime code for hot module replacement
+      "webpack/hot/dev-server.js",
+      // Dev server client for web socket transport, hot and live reload logic
+      "webpack-dev-server/client/index.js?hot=true&live-reload=true",
+      // Your entry
+      "./src/entry.js",
+    ],
+    plugin: [
+      // Plugin for hot module replacement
+      new webpack.HotModuleReplacementPlugin(),
+    ],
+  };
+  const compiler = webpack(config);
+  // `hot` and `client` options are disabled because we added them manually
+  const server = new DevServer({ hot: false, client: false }, compiler);
+
+  (async () => {
+    await server.start();
+
+    console.log("Running");
+  })();
+  ```
 
 ### Deprecations