Add "(i/total)" to shader compile progress

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/PreviewSystem.cs

             if (m_DirtyShaders.Any())
             {
                 PropagateNodeSet(m_DirtyShaders);
-                EditorUtility.DisplayProgressBar("Shader Graph", "Compiling preview shaders", 0f);
+                    EditorUtility.DisplayProgressBar("Shader Graph", string.Format("Compiling preview shaders ({0}/{1})", i, count), 0f);
-                        EditorUtility.DisplayProgressBar("Shader Graph", "Compiling preview shaders", (float)i / count);
+                        EditorUtility.DisplayProgressBar("Shader Graph", string.Format("Compiling preview shaders ({0}/{1})", i, count), 0f);
                     }
                 }
                 finally