test: add i18n test

test/unit/i18n_test.dart

@@ -0,0 +1,12 @@
+import 'package:localsend_app/gen/strings.g.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('i18n', () {
+    test('Should compile', () {
+      // The following test will fail if the i18n file is either not compiled
+      // or there are compile-time errors.
+      expect(AppLocale.en.translations.general.accept, 'Accept');
+    });
+  });
+}