3D Widget Components with depth test disabled are still culled when fully occluded

Currently, we allow occlusion culling on WidgetComponents regardless of whether or not depth test is enabled. This makes it challenging to make a widget render through other actors in the world, since the widget will be culled regardless of the fact that it should still be visible.

1. Create a widget component to display a widget in world space
2. Override the widget material to disable depth test
3. Place a mesh to fully cover the widget
4. The widget will disappear once fully covered