Move some files out of Content.Shared root because I forgot (#4182)

Content.Shared/Module/SharedModuleTestingCallbacks.cs

@@ -0,0 +1,11 @@
+#nullable enable
+using System;
+using Robust.Shared.ContentPack;
+
+namespace Content.Shared.Module
+{
+    public abstract class SharedModuleTestingCallbacks : ModuleTestingCallbacks
+    {
+        public Action SharedBeforeIoC { get; set; } = default!;
+    }
+}