Re-organize all projects (#4166)

Content.Shared/Module/IModuleManager.cs

@@ -0,0 +1,20 @@
+#nullable enable
+namespace Content.Shared.Module
+{
+    /// <summary>
+    /// Provides a simple way to check whether calling code is being run by
+    /// Robust.Client, or Robust.Server. Useful for code in Content.Shared
+    /// that wants different behavior depending on if client or server is using it.
+    /// </summary>
+    public interface IModuleManager
+    {
+        /// <summary>
+        /// Returns true if the code is being run by the client, returns false otherwise.
+        /// </summary>
+        bool IsClientModule { get; }
+        /// <summary>
+        /// Returns true if the code is being run by the server, returns false otherwise.
+        /// </summary>
+        bool IsServerModule { get; }
+    }
+}