Reduce atmos allocs a bunch (#7228)

Content.Server/Atmos/EntitySystems/AtmosObstructionEnumerator.cs

@@ -0,0 +1,36 @@
+using System.Diagnostics.CodeAnalysis;
+using Content.Server.Atmos.Components;
+using Robust.Shared.Map;
+
+namespace Content.Server.Atmos.EntitySystems;
+
+public struct AtmosObstructionEnumerator
+{
+    private AnchoredEntitiesEnumerator _enumerator;
+    private EntityQuery<AirtightComponent> _query;
+
+    public AtmosObstructionEnumerator(AnchoredEntitiesEnumerator enumerator, EntityQuery<AirtightComponent> query)
+    {
+        _enumerator = enumerator;
+        _query = query;
+    }
+
+    public bool MoveNext([NotNullWhen(true)] out AirtightComponent? airtight)
+    {
+        if (!_enumerator.MoveNext(out var uid))
+        {
+            airtight = null;
+            return false;
+        }
+
+        // No rider, it makes it uglier.
+        // ReSharper disable once ConvertIfStatementToReturnStatement
+        if (!_query.TryGetComponent(uid.Value, out airtight))
+        {
+            // ReSharper disable once TailRecursiveCall
+            return MoveNext(out airtight);
+        }
+
+        return true;
+    }
+}