Add generics to server add-on connection

Reviewed By: mweststrate

Differential Revision: D34307356

fbshipit-source-id: 27e61355a85995368ebb197c42d58f4145473567

desktop/flipper-common/src/index.tsx

@@ -47,6 +47,7 @@ export {
   getErrorFromErrorLike,
   deserializeRemoteError,
 } from './utils/errors';
+export {createControlledPromise} from './utils/controlledPromise';
 export * from './GK';
 export * from './clientUtils';
 export * from './settings';