Move IMayRequireNormal into own file

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/Input/Geometry/WorldSpaceNormalNode.cs

 
 namespace UnityEngine.MaterialGraph
 {
-    public interface IMayRequireNormal
-    {
-        bool RequiresNormal();
-    }
-
     [Title("Input/Geometry/World Normal")]
     public class WorldSpaceNormalNode : AbstractMaterialNode, IMayRequireNormal
     {

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Interfaces/IMayRequireNormal.cs

+namespace UnityEngine.MaterialGraph
+{
+    public interface IMayRequireNormal
+    {
+        bool RequiresNormal();
+    }
+}

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Interfaces/IMayRequireNormal.cs.meta

+fileFormatVersion: 2
+guid: 51bb8f11fbcf43f9bcec6418f1991397
+timeCreated: 1504092018