TF-1217 Load env file for fcm configuration

lib/main/utils/app_utils.dart

@@ -0,0 +1,15 @@
+import 'package:flutter_dotenv/flutter_dotenv.dart';
+import 'package:tmail_ui_user/main/utils/app_config.dart';
+
+class AppUtils {
+
+  static const String envFileName = 'env.file';
+
+  static Future<void> loadEnvFile()  {
+    return dotenv.load(fileName: envFileName);
+  }
+
+  static Future<void> loadFcmConfigFile()  {
+    return dotenv.load(fileName: AppConfig.appFCMConfigurationPath);
+  }
+}