build(ReactTransitionGroup): Externalize ReactTransitionGroup (fixes big file size) (reactstrap#474)

* Externalize ReactTransitionGroup

* Update transition group imports

* Revert incorrect fix reactstrap#433

* Revert change to main and fix in future PR.

Author: balloob

rollup.config.js

@@ -24,6 +24,7 @@ const config = {
   globals: {
     react: 'React',
     'react-dom': 'ReactDOM',
+    'react-transition-group': 'ReactTransitionGroup',
   },
   targets: [
     { dest: 'dist/reactstrap.es.js', format: 'es' },

src/Alert.js

@@ -1,7 +1,7 @@
 import React from 'react';
 import PropTypes from 'prop-types';
 import classNames from 'classnames';
-import CSSTransitionGroup from 'react-transition-group/CSSTransitionGroup';
+import { CSSTransitionGroup } from 'react-transition-group';
 import { mapToCssModules } from './utils';
 
 const FirstChild = ({ children }) => (

src/Modal.js

@@ -2,7 +2,7 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import ReactDOM from 'react-dom';
 import classNames from 'classnames';
-import TransitionGroup from 'react-transition-group/TransitionGroup';
+import { TransitionGroup } from 'react-transition-group';
 import Fade from './Fade';
 import {
   getOriginalBodyPadding,