Add RestApiUtility Class for HTTP Requests

This commit introduces a new utility class, RestApiUtility, designed to encapsulate all the HTTP request operations.

- Created RestApiUtility class with a constructor that accepts a base URL.
- Added get method to perform GET requests and return data as a Map.
- Added getList method to perform GET requests and return data as a List.
- Added post method to perform POST requests with payload and return data as a Map.

The class uses the http package for making network calls and dart:convert for JSON serialization and deserialization. This centralized approach makes it easier to manage API calls and handle errors across the application.

lib/utils/rest_api_utility.dart

@@ -0,0 +1,40 @@
+import 'dart:convert';
+import 'package:http/http.dart' as http;
+
+class RestApiUtility {
+  final String baseUrl;
+
+  RestApiUtility(this.baseUrl);
+
+  Future<Map<String, dynamic>> get(String endpoint) async {
+    final response = await http.get(Uri.parse('$baseUrl/$endpoint'));
+    if (response.statusCode == 200) {
+      return json.decode(response.body);
+    } else {
+      throw Exception('Failed to load data');
+    }
+  }
+
+  Future<List<dynamic>> getList(String endpoint) async {
+    final response = await http.get(Uri.parse('$baseUrl/$endpoint'));
+    if (response.statusCode == 200) {
+      return json.decode(response.body);
+    } else {
+      throw Exception('Failed to load data');
+    }
+  }
+
+  Future<Map<String, dynamic>> post(
+      String endpoint, Map<String, dynamic> payload) async {
+    final response = await http.post(
+      Uri.parse('$baseUrl/$endpoint'),
+      body: json.encode(payload),
+      headers: {"Content-Type": "application/json"},
+    );
+    if (response.statusCode == 200 || response.statusCode == 201) {
+      return json.decode(response.body);
+    } else {
+      throw Exception('Failed to post data');
+    }
+  }
+}