refactor: use Next.js for demo

apps/demo/components/command-bar.tsx

@@ -0,0 +1,16 @@
+import { CommandBar as FluentCommandBar, ICommandBarProps, StackItem } from '@fluentui/react';
+import { withDisplayName } from '../utils/with-display-name';
+
+const ContainerStyles = {
+    root: {
+        borderBottom: '1px solid rgb(243, 242, 241)',
+    }
+} as const;
+
+export const CommandBar = withDisplayName('CommandBar')((props: ICommandBarProps) => {
+    return (
+        <StackItem styles={ContainerStyles}>
+            <FluentCommandBar {...props} />
+        </StackItem>
+    );
+});