Exposed shared property HttpServer bind method to support more use-cases.

lib/src/in_app_localhost_server.dart

@@ -17,6 +17,7 @@ class InAppLocalhostServer {
   bool _started = false;
   HttpServer? _server;
   int _port = 8080;
+  bool _shared = false;
   String _directoryIndex = 'index.html';
   String _documentRoot = './';
 
@@ -25,15 +26,24 @@ class InAppLocalhostServer {
   ///- [directoryIndex] represents the index file to use. The default value is `index.html`.
   ///
   ///- [documentRoot] represents the document root path to serve. The default value is `./`.
+  ///
+  ///- The optional argument [shared] specifies whether additional `HttpServer`
+  /// objects can bind to the same combination of `address`, `port` and `v6Only`.
+  /// If `shared` is `true` and more `HttpServer`s from this isolate or other
+  /// isolates are bound to the port, then the incoming connections will be
+  /// distributed among all the bound `HttpServer`s. Connections can be
+  /// distributed over multiple isolates this way.
   InAppLocalhostServer({
     int port = 8080,
     String directoryIndex = 'index.html',
     String documentRoot = './',
+    bool shared = false,
   }) {
     this._port = port;
     this._directoryIndex = directoryIndex;
     this._documentRoot =
         (documentRoot.endsWith('/')) ? documentRoot : '$documentRoot/';
+    this._shared = shared;
   }
 
   ///Starts the server on `http://localhost:[port]/`.
@@ -57,7 +67,7 @@ class InAppLocalhostServer {
     var completer = Completer();
 
     runZonedGuarded(() {
-      HttpServer.bind('127.0.0.1', _port).then((server) {
+      HttpServer.bind('127.0.0.1', _port, shared: _shared).then((server) {
         print('Server running on http://localhost:' + _port.toString());
 
         this._server = server;