Rework wheelchairbound (#24173)

* Rework wheelchairbound

Fixes the save/load bug and fixes it being a singleton.

* weh

Content.Server/Traits/Assorted/BuckleOnMapInitComponent.cs

@@ -0,0 +1,14 @@
+using Robust.Shared.Prototypes;
+
+namespace Content.Server.Traits.Assorted;
+
+/// <summary>
+/// Upon MapInit buckles the attached entity to a newly spawned prototype.
+/// </summary>
+[RegisterComponent, Access(typeof(BuckleOnMapInitSystem))]
+public sealed partial class BuckleOnMapInitComponent : Component
+{
+    [ViewVariables(VVAccess.ReadWrite)]
+    [DataField(required: true)]
+    public EntProtoId Prototype;
+}