Travelling pointing arrows, brains can no longer point (#24864)

* Decoupled from gravity, constant animation time, manual networking, cubic interpolation

* Reduced overshoot

* Implemented PointAttemptEvent, reacts with mobstate & sleeping

* Brains can no longer point, PBs must be inside a chassis

* Removed chassis check, made callback more obvious

Content.Shared/Pointing/Components/SharedPointingArrowComponent.cs

@@ -1,13 +1,22 @@
 using Robust.Shared.GameStates;
+using System.Numerics;
 
 namespace Content.Shared.Pointing.Components;
 
 [NetworkedComponent]
 public abstract partial class SharedPointingArrowComponent : Component
 {
+    /// <summary>
+    /// The position of the sender when the point began.
+    /// </summary>
+    [DataField]
+    [ViewVariables(VVAccess.ReadWrite)]
+    public Vector2 StartPosition;
+
     /// <summary>
     /// When the pointing arrow ends
     /// </summary>
-    [ViewVariables(VVAccess.ReadWrite), DataField("endTime")]
+    [DataField]
+    [ViewVariables(VVAccess.ReadWrite)]
     public TimeSpan EndTime;
 }