Basic desktop plugin

Summary:
Scaffolded desktop UI for UI debugger
I changed getroot from an rpc call to an event sent on connect. The root should never change as its the application object.

Reviewed By: lblasa

Differential Revision: D38866008

fbshipit-source-id: ca0f1908bedb643238f11ed796922e3359619167

desktop/plugins/public/ui-debugger/components/main.tsx

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import React from 'react';
+import {plugin} from '../index';
+import {usePlugin, useValue} from 'flipper-plugin';
+
+export function Component() {
+  const instance = usePlugin(plugin);
+  const rootId = useValue(instance.rootId);
+
+  return <div>{rootId}</div>;
+}