Introduce createTablePlugin

Summary: This diff exposes the createTablePlugin from flipper-plugin, so that createTablePlugin based plugins can be converted to Sandy as well

Reviewed By: jknoxville

Differential Revision: D28031227

fbshipit-source-id: 8e9c82da08a83fddab740b46be9917b6a1023117

desktop/flipper-plugin/src/plugin/Plugin.tsx

@@ -12,7 +12,7 @@ import {BasePluginInstance, BasePluginClient} from './PluginBase';
 import {FlipperLib} from './FlipperLib';
 import {RealFlipperDevice} from './DevicePlugin';
 import {batched} from '../state/batch';
-import {Atom, createState} from '../state/atom';
+import {Atom, createState, ReadOnlyAtom} from '../state/atom';
 
 type EventsContract = Record<string, any>;
 type MethodsContract = Record<string, (params: any) => Promise<any>>;
@@ -40,6 +40,7 @@ export interface PluginClient<
   readonly appName: string;
 
   readonly isConnected: boolean;
+  readonly connected: ReadOnlyAtom<boolean>;
 
   /**
    * the onConnect event is fired whenever the plugin is connected to it's counter part on the device.
@@ -169,6 +170,7 @@ export class SandyPluginInstance extends BasePluginInstance {
       get appName() {
         return realClient.query.app;
       },
+      connected: self.connected,
       get isConnected() {
         return self.connected.get();
       },