Add mob retaliation (#19901)

Content.Server/NPC/Components/NPCRetaliationComponent.cs

@@ -0,0 +1,24 @@
+using Content.Server.NPC.Systems;
+
+namespace Content.Server.NPC.Components;
+
+/// <summary>
+/// Entities with this component will retaliate against those who physically attack them.
+/// It has an optional "memory" specification wherein it will only attack those entities for a specified length of time.
+/// </summary>
+[RegisterComponent, Access(typeof(NPCRetaliationSystem))]
+public sealed partial class NPCRetaliationComponent : Component
+{
+    /// <summary>
+    /// How long after being attacked will an NPC continue to be aggressive to the attacker for.
+    /// </summary>
+    [DataField("attackMemoryLength"), ViewVariables(VVAccess.ReadWrite)]
+    public TimeSpan? AttackMemoryLength;
+
+    /// <summary>
+    /// A dictionary that stores an entity and the time at which they will no longer be considered hostile.
+    /// </summary>
+    /// todo: this needs to support timeoffsetserializer at some point
+    [DataField("attackMemories")]
+    public Dictionary<EntityUid, TimeSpan> AttackMemories = new();
+}