feat: imported from @tanstack/router base vite-plugin logic

packages/vite-fs-router/tests/snapshots/default-exported?split.tsx

@@ -0,0 +1,3 @@
+export default function Route(): JSX.Element {
+  return <h1>Test route</h1>;
+}

packages/vite-fs-router/tests/snapshots/function-export?split.tsx

@@ -0,0 +1,4 @@
+function PostsRoute() {
+  return <h1>Post route</h1>;
+}
+export default PostsRoute;

packages/vite-fs-router/tests/snapshots/imported?split.tsx

@@ -0,0 +1,2 @@
+import { ImportedRoute } from '../shared/imported';
+export default ImportedRoute;