Update content to remove redundant Robust math types (#38930)

Vector3, Vector4, Matrix4, and Quaternion are now gone. This switches us over to System.Numerics where applicable.

Content.Client/UserInterface/Systems/DamageOverlays/Overlays/DamageOverlay.cs

@@ -1,3 +1,4 @@
+using System.Numerics;
 using Content.Shared.Mobs;
 using Robust.Client.Graphics;
 using Robust.Client.Player;