TF-3449 Add integration test for send email with mark as important

Signed-off-by: dab246 <tdvu@linagora.com>

integration_test/tests/compose/send_email_with_mark_as_important_test.dart

@@ -0,0 +1,9 @@
+import '../../base/test_base.dart';
+import '../../scenarios/send_email_with_mark_as_important_scenario.dart';
+
+void main() {
+  TestBase().runPatrolTest(
+    description: 'Should see email item has important flag icon when send email with mark as important successfully',
+    scenarioBuilder: ($) => SendEmailWithMarkAsImportantScenario($),
+  );
+}