Separate destructible component threshold into behaviors (#2818)

* WIP changes, add behaviors

* Fix behavior typing, namespace and test

* NO SPACES

Content.Server/GameObjects/Components/Destructible/Thresholds/Behavior/SpawnEntitiesBehavior.cs

@@ -0,0 +1,51 @@
+#nullable enable
+using System.Collections.Generic;
+using Content.Server.GameObjects.Components.Stack;
+using Content.Server.GameObjects.EntitySystems;
+using Content.Shared.Utility;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Serialization;
+
+namespace Content.Server.GameObjects.Components.Destructible.Thresholds.Behavior
+{
+    public class SpawnEntitiesBehavior : IThresholdBehavior
+    {
+        /// <summary>
+        ///     Entities spawned on reaching this threshold, from a min to a max.
+        /// </summary>
+        public Dictionary<string, MinMax> Spawn { get; set; } = new();
+
+        public void ExposeData(ObjectSerializer serializer)
+        {
+            serializer.DataField(this, x => x.Spawn, "spawn", new Dictionary<string, MinMax>());
+        }
+
+        public void Trigger(IEntity owner, DestructibleSystem system)
+        {
+            foreach (var (entityId, minMax) in Spawn)
+            {
+                var count = minMax.Min >= minMax.Max
+                    ? minMax.Min
+                    : system.Random.Next(minMax.Min, minMax.Max + 1);
+
+                if (count == 0) continue;
+
+                if (EntityPrototypeHelpers.HasComponent<StackComponent>(entityId))
+                {
+                    var spawned = owner.EntityManager.SpawnEntity(entityId, owner.Transform.Coordinates);
+                    var stack = spawned.GetComponent<StackComponent>();
+                    stack.Count = count;
+                    spawned.RandomOffset(0.5f);
+                }
+                else
+                {
+                    for (var i = 0; i < count; i++)
+                    {
+                        var spawned = owner.EntityManager.SpawnEntity(entityId, owner.Transform.Coordinates);
+                        spawned.RandomOffset(0.5f);
+                    }
+                }
+            }
+        }
+    }
+}