Remove ignore-inside-blocker (#6692)

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.Shared/Construction/SharedConstructionSystem.cs

@@ -1,13 +1,29 @@
-using System;
-using Robust.Shared.GameObjects;
+using System.Linq;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
 using Robust.Shared.Serialization;
+using static Content.Shared.Interaction.SharedInteractionSystem;
 
 namespace Content.Shared.Construction
 {
     public abstract class SharedConstructionSystem : EntitySystem
     {
+        [Dependency] private readonly IMapManager _mapManager = default!;
+
+        /// <summary>
+        ///     Get predicate for construction obstruction checks.
+        /// </summary>
+        public Ignored? GetPredicate(bool canBuildInImpassable, MapCoordinates coords)
+        {
+            if (!canBuildInImpassable)
+                return null;
+
+            if (!_mapManager.TryFindGridAt(coords, out var grid))
+                return null;
+
+            var ignored = grid.GetAnchoredEntities(coords).ToHashSet();
+            return e => ignored.Contains(e);
+        }
+
         /// <summary>
         ///     Sent client -> server to to tell the server that we started building
         ///     a structure-construction.