Add AlwaysOnBottom support for Windows (#306)

* feat: add isAlwaysOnBottom & setAlwaysOnBottom support for Windows

* chore: add generated files to gitignore

* chore: remove gitignored files

Author: Merrit

.gitignore

@@ -5,3 +5,5 @@
 .pub/
 .vscode/
 build/
+Generated*
+generated*

README.md

@@ -83,7 +83,7 @@ English | [简体中文](./README-ZH.md)
       - [isAlwaysOnTop](#isalwaysontop)
       - [setAlwaysOnTop](#setalwaysontop)
       - [isAlwaysOnBottom](#isalwaysonbottom)
-      - [setAlwaysOnBottom  `linux`](#setalwaysonbottom--linux)
+      - [setAlwaysOnBottom  `linux` `windows`](#setalwaysonbottom--linux--windows)
       - [getTitle](#gettitle)
       - [setTitle](#settitle)
       - [setTitleBarStyle](#settitlebarstyle)

example/lib/pages/home.dart

@@ -648,9 +648,9 @@ class _HomePageState extends State<HomePage> with TrayListener, WindowListener {
                 BotToast.showText(text: 'isAlwaysOnBottom: $isAlwaysOnBottom');
               },
               value: _isAlwaysOnBottom,
-              onChanged: (newValue) {
+              onChanged: (newValue) async {
                 _isAlwaysOnBottom = newValue;
-                windowManager.setAlwaysOnBottom(_isAlwaysOnBottom);
+                await windowManager.setAlwaysOnBottom(_isAlwaysOnBottom);
                 setState(() {});
               },
             ),