Let PopupOnTrigger display names of user and item (#41157)

* waved away

* waves at you with my [Prime Cut Corgi Meat]

* pls dont litter the repository with unnecessary components

* forgot to remove a variable from testing

* guh

* the more things change, the more things stay the same

* and then she ternaried everywhere

* owie

Content.Shared/Trigger/Components/Effects/PopupOnTriggerComponent.cs

@@ -5,6 +5,9 @@ namespace Content.Shared.Trigger.Components.Effects;
 
 /// <summary>
 /// Displays a popup on the target when triggered.
+/// Supports following fluent variables:
+///     $entity - displays the target entity's name
+///     $user - displays the user's name
 /// Will display the popup on the user when <see cref="BaseXOnTriggerComponent.TargetUser"/> is true.
 /// </summary>
 [RegisterComponent, NetworkedComponent, AutoGenerateComponentState]