PR-753737: moviendo toda la logica de front-end a src.

src/frontend/components/App.jsx

@@ -0,0 +1,5 @@
+import React from 'react';
+
+const App = () => <h1>Hello React!</h1>
+
+export default App;

src/frontend/index.js

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+import React from 'react';
+import ReactDom from 'react-dom';
+import App from './components/App';
+import './styles/global.sass';
+
+ReactDom.render(<App />, document.getElementById('app'));

src/frontend/styles/global.sass

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+$base-color: #c6538c
+$color: rgba(black, 0.88)
+
+body
+    background-color: $base-color
+    color: $color