Fix disabled Dropdown Items not showing Popup component

[juanmahidalgo]

For the src/components/CollectionDetailPage/CollectionContextMenu/CollectionContextMenu.tsx component, the Popup are not being displayed when the Dropdown.item is disabled. There is a similar use case and a fix was introduced here. We need to move that same workaround to a /src/themes/components/Dropdown.cs so we fix it everywhere.