TF-3410 Change color of icons in TopAppBarThreadSelection

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

lib/features/mailbox_dashboard/presentation/styles/top_bar_thread_selection_style.dart

@@ -0,0 +1,9 @@
+
+import 'package:core/presentation/extensions/color_extension.dart';
+import 'package:flutter/material.dart';
+
+class TopBarThreadSelectionStyle {
+  static const Color iconColor = AppColor.steelGrayA540;
+
+  static const double iconSize = 20.0;
+}