Add SideBarView with Toggleable Icons

frontend/lib/views/side_bar_view.dart

@@ -0,0 +1,41 @@
+import 'package:flutter/material.dart';
+
+class SideBarView extends StatelessWidget {
+  final ValueNotifier<String> selectedViewNotifier;
+
+  SideBarView({required this.selectedViewNotifier});
+
+  @override
+  Widget build(BuildContext context) {
+    return Material(
+      child: ValueListenableBuilder(
+          valueListenable: selectedViewNotifier,
+          builder: (context, String selectedView, _) {
+            return SizedBox(
+              width: 60,
+              child: Column(
+                mainAxisAlignment: MainAxisAlignment.start,
+                children: [
+                  IconButton(
+                    splashRadius: 0.1,
+                    color:
+                        selectedView == 'TaskView' ? Colors.blue : Colors.black,
+                    icon: Icon(Icons.chat),
+                    onPressed: () => selectedViewNotifier.value = 'TaskView',
+                  ),
+                  IconButton(
+                    splashRadius: 0.1,
+                    color: selectedView == 'SkillTreeView'
+                        ? Colors.blue
+                        : Colors.black,
+                    icon: Icon(Icons.emoji_events), // trophy icon
+                    onPressed: () =>
+                        selectedViewNotifier.value = 'SkillTreeView',
+                  ),
+                ],
+              ),
+            );
+          }),
+    );
+  }
+}