Expeditions rework (#18960)

Content.Shared/Random/IBudgetEntry.cs

@@ -0,0 +1,20 @@
+namespace Content.Shared.Random;
+
+/// <summary>
+/// Budgeted random spawn entry.
+/// </summary>
+public interface IBudgetEntry : IProbEntry
+{
+    float Cost { get; set; }
+
+    string Proto { get; set; }
+}
+
+/// <summary>
+/// Random entry that has a prob. See <see cref="RandomSystem"/>
+/// </summary>
+public interface IProbEntry
+{
+    float Prob { get; set; }
+}
+