Entity Tables (EntitySpawnEntry replacement) (#30579)

* Entity table code

* entity table examples

* fix dat shit

* access

* tests tests tests

* sloth review

Content.Shared/EntityTable/EntitySelectors/EntSelector.cs

@@ -0,0 +1,27 @@
+using Content.Shared.EntityTable.ValueSelector;
+using Robust.Shared.Prototypes;
+
+namespace Content.Shared.EntityTable.EntitySelectors;
+
+/// <summary>
+/// Gets the spawn for the entity prototype specified at whatever count specified.
+/// </summary>
+public sealed partial class EntSelector : EntityTableSelector
+{
+    [DataField(required: true)]
+    public EntProtoId Id;
+
+    [DataField]
+    public NumberSelector Amount = new ConstantNumberSelector(1);
+
+    protected override IEnumerable<EntProtoId> GetSpawnsImplementation(System.Random rand,
+        IEntityManager entMan,
+        IPrototypeManager proto)
+    {
+        var num = (int) Math.Round(Amount.Get(rand, entMan, proto));
+        for (var i = 0; i < num; i++)
+        {
+            yield return Id;
+        }
+    }
+}