Separate the concepts of archived and disconnected devices

Summary:
Minor code cleanup to avoid future confusion:

- archived: a device that was imported from a Flipper trace, and only has persisted state
- (dis)connected: a real stateful device that might or might not have an active connection

Reviewed By: nikoant

Differential Revision: D26275459

fbshipit-source-id: eba554b37c39711e367c3795ff4456329a303c22

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

@@ -11,6 +11,7 @@ import {SandyPluginDefinition} from './SandyPluginDefinition';
 import {BasePluginInstance, BasePluginClient} from './PluginBase';
 import {FlipperLib} from './FlipperLib';
 import {DeviceType as PluginDeviceType} from 'flipper-plugin-lib';
+import {Atom} from '../state/atom';
 
 export type DeviceLogListener = (entry: DeviceLogEntry) => void;
 
@@ -67,6 +68,7 @@ export interface RealFlipperDevice {
   os: string;
   serial: string;
   isArchived: boolean;
+  connected: Atom<boolean>;
   deviceType: DeviceType;
   addLogListener(callback: DeviceLogListener): Symbol;
   removeLogListener(id: Symbol): void;