Qt: Fix column resolve names

Reset columns when resolve names column menu item is toggled,
and save preferences to preserve the setting.

We should probably have functions to redraw only one column.

Change-Id: I52dce8d104ab9bedd11edc5d200ab85154243cb5
Reviewed-on: https://code.wireshark.org/review/12077
Reviewed-by: Stig Bjørlykke <stig@bjorlykke.org>

ui/qt/packet_list.cpp

@@ -1177,6 +1177,10 @@ void PacketList::headerMenuTriggered()
         break;
     case caResolveNames:
         set_column_resolved(header_ctx_column_, checked);
+        packet_list_model_->resetColumns();
+        if (!prefs.gui_use_pref_save) {
+            prefs_main_write();
+        }
         redraw = true;
         break;
     case caResizeToContents: