feat: add sample in web app.

demo/Semi.Avalonia.Demo.Web/AppBundle/main.js

@@ -0,0 +1,16 @@
+import { dotnet } from './dotnet.js'
+import { registerAvaloniaModule } from './avalonia.js';
+
+const is_browser = typeof window != "undefined";
+if (!is_browser) throw new Error(`Expected to be running in a browser`);
+
+const dotnetRuntime = await dotnet
+    .withDiagnosticTracing(false)
+    .withApplicationArgumentsFromQuery()
+    .create();
+
+await registerAvaloniaModule(dotnetRuntime);
+
+const config = dotnetRuntime.getConfig();
+
+await dotnetRuntime.runMainAndExit(config.mainAssemblyName, [window.location.search]);