message: chore(devenv): fix manager webpack config
  The manager code is written in React for all regardless of the
  JavaScript framework being demonstrated, and thus `@babel/preset-react`
  instead of `babel-preset-vue` must be used.
  The symptom is seen with theme switcher enabled with
  `CARBON_CUSTOM_ELEMENTS_STORYBOOK_USE_CUSTOM_PROPERTIES=true`
  environment variable.
diff: @@ -4,6 +4,21 @@ const webpack = require('webpack');
  module.exports = {
  async managerWebpack(config) {
  + const babelLoaderRule = config.module.rules.find(
  + item => item.use && item.use.some && item.use.some(use => /babel-loader/i.test(use.loader))
  + );
  + if (babelLoaderRule) {
  + babelLoaderRule.use.forEach(item => {
  + const { presets } = item.options || {};
  + if (presets) {
  + const vuePresetIndex = presets.findIndex(preset => /babel-preset-vue/i.test(preset));
  + if (vuePresetIndex >= 0) {
  + // Given this is a manager, JSX must be handled by REact
  + presets.splice(vuePresetIndex, 1, '@babel/preset-react');
  + }
  + }
  + });
  + }
  // `@storybook/react` NPM installation seems to add `@babel/preset-react` automatically
  config.plugins.push(
  new webpack.EnvironmentPlugin({
  