ECS dragdrop (#12973)

* ECS dragdrop

No more excuses.

* AAAAAAAAAAAAAA

* kry

* events

* aaaaaaaaaa

* HUH

* Fix stripping

* aaaaaa

* spoike

* asease

* fix table vaulting

* ded

* rebiew

* aaaaaaaaaaaaa

* drag

* aeaeae

* weh

Content.Shared/DragDrop/DraggableEvents.cs

@@ -0,0 +1,67 @@
+namespace Content.Shared.DragDrop;
+
+/// <summary>
+/// Raised directed on an entity when attempting to start a drag.
+/// </summary>
+[ByRefEvent]
+public record struct CanDragEvent
+{
+    /// <summary>
+    /// False if we are unable to drag this entity.
+    /// </summary>
+    public bool Handled;
+}
+
+/// <summary>
+/// Raised directed on a dragged entity to indicate whether it has interactions with the target entity.
+/// </summary>
+[ByRefEvent]
+public record struct CanDropDraggedEvent(EntityUid User, EntityUid Target)
+{
+    public readonly EntityUid User = User;
+    public readonly EntityUid Target = Target;
+    public bool Handled = false;
+
+    /// <summary>
+    /// Can we drop the entity onto the target? If the event is not handled then there is no supported interactions.
+    /// </summary>
+    public bool CanDrop = false;
+}
+
+/// <summary>
+/// Raised directed on the target entity to indicate whether it has interactions with the dragged entity.
+/// </summary>
+[ByRefEvent]
+public record struct CanDropTargetEvent(EntityUid User, EntityUid Dragged)
+{
+    public readonly EntityUid User = User;
+    public readonly EntityUid Dragged = Dragged;
+    public bool Handled = false;
+
+    /// <summary>
+    /// <see cref="CanDropDraggedEvent"/>
+    /// </summary>
+    public bool CanDrop = false;
+}
+
+/// <summary>
+/// Raised directed on a dragged entity when it is dropped on a target entity.
+/// </summary>
+[ByRefEvent]
+public record struct DragDropDraggedEvent(EntityUid User, EntityUid Target)
+{
+    public readonly EntityUid User = User;
+    public readonly EntityUid Target = Target;
+    public bool Handled = false;
+}
+
+/// <summary>
+/// Raised directed on the target entity when a dragged entity is dragged onto it.
+/// </summary>
+[ByRefEvent]
+public record struct DragDropTargetEvent(EntityUid User, EntityUid Dragged)
+{
+    public readonly EntityUid User = User;
+    public readonly EntityUid Dragged = Dragged;
+    public bool Handled = false;
+}