implement a multi-file template interpreter

examples/react-app-generator/templates/app-component.tmpl

@@ -0,0 +1,13 @@
+import React from 'react';
+import AppRouter from './router';
+// import './App.css';
+
+function App() {
+  return (
+    <div className="App">
+      <AppRouter />
+    </div>
+  );
+}
+
+export default App;