NPC refactor (#10122)

Co-authored-by: metalgearsloth <metalgearsloth@gmail.com>

Content.Server/NPC/HTN/Preconditions/HTNPrecondition.cs

@@ -0,0 +1,22 @@
+namespace Content.Server.NPC.HTN.Preconditions;
+
+/// <summary>
+/// Condition that needs to be true for a particular primitive task or compound task branch.
+/// </summary>
+[ImplicitDataDefinitionForInheritors]
+public abstract class HTNPrecondition
+{
+    /// <summary>
+    /// Handles one-time initialization of this precondition.
+    /// </summary>
+    /// <param name="sysManager"></param>
+    public virtual void Initialize(IEntitySystemManager sysManager)
+    {
+        IoCManager.InjectDependencies(this);
+    }
+
+    /// <summary>
+    /// Has this precondition been met for planning purposes?
+    /// </summary>
+    public abstract bool IsMet(NPCBlackboard blackboard);
+}