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/index.tsx

@@ -0,0 +1,22 @@
+/**
+ * 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 {PluginClient, createState} from 'flipper-plugin';
+
+type Events = {
+  init: {rootId: string};
+};
+
+export function plugin(client: PluginClient<Events>) {
+  const rootId = createState<string | undefined>(undefined);
+  client.onMessage('init', (root) => rootId.set(root.rootId));
+  return {rootId};
+}
+
+export {Component} from './components/main';