Displaying multiple pickups of different objects as text totals via a dynamic Dictionary<> of PickUp objects and enum pickup types

While the previous recipe worked fine, any old text could have been typed into the description of a pickup or perhaps mistyped (star, Sstar, starr, and so on). A much better way of restricting game properties to one of a predefined (enumerated) list of possible values is to use C# enums. As well as removing the possibility of mistyping a string, it also means that we can write code to deal with the predefined set of possible values. In this recipe, we will improve our general-purpose PickUp class by introducing three possible pickup types (Star, Heart, and Key), and write inventory display code that counts the number of each type of pickup being carried before displaying these totals via a UI Text object on the screen. We will also switch from using a List to using a Dictionary, since the Dictionary data structure is designed specifically for key...