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>;
+}

desktop/plugins/public/ui-debugger/docs/overview.mdx

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+This is an experimental plugin in development. Everything will change and comes with no warranty / support guarantees

desktop/plugins/public/ui-debugger/index.tsx

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+/**
+ * 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';

desktop/plugins/public/ui-debugger/package.json

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+{
+  "$schema": "https://fbflipper.com/schemas/plugin-package/v2.json",
+  "name": "flipper-plugin-ui-debugger",
+  "id": "ui-debugger",
+  "pluginType": "client",
+  "version": "0.0.0",
+  "flipperBundlerEntry": "index.tsx",
+  "main": "dist/bundle.js",
+  "license": "MIT",
+  "title": "UI Debugger (alpha)",
+  "icon": "nav-magnifying-glass",
+  "keywords": [
+    "flipper-plugin"
+  ],
+  "bugs": {
+    "url": "https://github.com/facebook/flipper/issues"
+  },
+  "peerDependencies": {
+    "flipper-plugin": "*",
+    "antd": "*",
+    "react": "*",
+    "react-dom": "*",
+    "@emotion/styled": "*",
+    "@ant-design/icons": "*",
+    "@types/react": "*",
+    "@types/react-dom": "*",
+    "@types/node": "*"
+  }
+}