Store collapsed status of sidebar sections

Summary:
See previous diff, let's store the collapsed state of sidebar sections in local storage.

Introduced a reusable hook to take care of that.

Changelog: Device plugins are now expanded by default, and the expand / collapse state will now be remembered across restarts

Reviewed By: passy

Differential Revision: D21903394

fbshipit-source-id: a3c0231acc0aa0877522ec328eedd09cb11aedb1

desktop/app/src/index.tsx

@@ -188,3 +188,4 @@ export {getFlipperMediaCDN} from './fb-stubs/user';
 export {Rect} from './utils/geometry';
 export {Logger} from './fb-interfaces/Logger';
 export {callVSCode, getVSCodeUrl} from './utils/vscodeUtils';
+export {useLocalStorage} from './utils/useLocalStorage';