core&ui: add connection heartbeat

packages/ui-default/api.ts

@@ -6,6 +6,7 @@ export * from './components/dialog';
 export { Context, Service, ctx } from './context';
 export { default as AnsiUp } from 'ansi_up';
 export { default as loadMonaco } from './components/monaco/loader';
+export { default as Socket } from './components/socket/index';
 export { default as uploadFiles } from './components/upload';
 export * as redux from 'react-redux';
 export * from './components/zipDownloader';