HUD Health Widget Implementation

[wail]

Our current HUD Health Display Widget (BP_Widget_Health) implementation has these problems:

Issues:

• It is created & positioned as part of another widget
  • Problem: A singular master-widget will become a bottleneck for development in the future
• Widget Dependencies: This widget inherits from other widgets and contains other subwidgets
  • Problem: Widget inheritance sucks in Unreal. If we need base-level functionality lets make a C++ widget class to handle this. It is also is too complex to figure out what is going on with this widget for how simple it is.
• Gameplay Class Dependencies: This widget directly queries our GAS ASC HealthAttribute.
  • Problem: We don't want our UI to directly depend on our gameplay classes like this, especially because it should be very simple to use the GameplayMessageSubsystem to broadcast HealthAttribute changes to the UI and thus avoid any direct dependencies.

Subtasks

• The HUD Health Widget should be created via a GameFeatureAction_AddWidget which adds a HUD widget to the Experience
• The HUD Health Widget should be spawned into a widget called the StandardHUD utilizing a soft-linkage of GameplayTag to slot the widget into a predefined position
• Simplify the architecture of the HUD Health Widget (add C++ base class if necessary)
• Add GameplayMessage to communicate data between HealthComponent/HealthAttribute and Widget