Move DetailSidebar to flipper-plugin

Summary: This moves `<DetailSidebar>` component to `flipper-plugin` and documents it. No semantic changes.

Reviewed By: passy

Differential Revision: D27234575

fbshipit-source-id: 74640602d718f84ad999f5dac0420089796ed7fb

desktop/app/src/utils/flipperLibImplementation.tsx

@@ -17,6 +17,7 @@ import {clipboard} from 'electron';
 import constants from '../fb-stubs/constants';
 import {addNotification} from '../reducers/notifications';
 import {deconstructPluginKey} from './clientUtils';
+import {DetailSidebarImpl} from '../sandy-chrome/DetailSidebarImpl';
 
 export function initializeFlipperLibImplementation(
   store: Store,
@@ -83,5 +84,6 @@ export function initializeFlipperLibImplementation(
         }),
       );
     },
+    DetailsSidebarImplementation: DetailSidebarImpl,
   });
 }