Entity Tables (EntitySpawnEntry replacement) (#30579)

* Entity table code

* entity table examples

* fix dat shit

* access

* tests tests tests

* sloth review

Content.Shared/EntityTable/ValueSelector/ConstantNumberSelector.cs

@@ -0,0 +1,22 @@
+using Robust.Shared.Prototypes;
+
+namespace Content.Shared.EntityTable.ValueSelector;
+
+/// <summary>
+/// Gives a constant value.
+/// </summary>
+public sealed partial class ConstantNumberSelector : NumberSelector
+{
+    [DataField]
+    public float Value = 1;
+
+    public ConstantNumberSelector(float value)
+    {
+        Value = value;
+    }
+
+    public override float Get(System.Random rand, IEntityManager entMan, IPrototypeManager proto)
+    {
+        return Value;
+    }
+}