Show Micro-/Nanoflow return types in the Project Explorer

The idea is to add iconography to the Project Explorer that shows at a glance the return type of a microflow or nanoflow. I think this additional layer of detail would promote a better developer experience.

Bonus feature: have an option in Preferences or in the Project Explorer to toggle the display of these icons

See expert rendering below (the text on the right is for reference and would not be a property of this feature).