add discount api

lib/data/provider/common_data_provider.dart

@@ -1,3 +1,4 @@
+import 'package:fcs/domain/entities/discount.dart';
 import 'package:fcs/domain/entities/payment_method.dart';
 import 'package:fcs/domain/vo/message.dart';
 import 'package:fcs/helpers/api_helper.dart';
@@ -32,4 +33,19 @@ class CommonDataProvider {
         payload: {"owner_id": ownerID, "seen_by_owner": seenByOwner},
         token: await getToken());
   }
+
+  Future<void> createDiscount(Discount discount) async {
+    return await requestAPI("/discounts", "POST",
+        payload: discount.toMap(), token: await getToken());
+  }
+
+  Future<void> updateDiscount(Discount discount) async {
+    return await requestAPI("/discounts", "PUT",
+        payload: discount.toMap(), token: await getToken());
+  }
+
+  Future<void> deleteDiscount(String id) async {
+    return await requestAPI("/discounts", "DELETE",
+        payload: {"id": id}, token: await getToken());
+  }
 }