Add getOutputDims to 2d layers

include/layers/conv2d.cuh

@@ -13,7 +13,7 @@ namespace CUDANet::Layers {
  * @brief 2D convolutional layer
  *
  */
-class Conv2d : public WeightedLayer {
+class Conv2d : public WeightedLayer, public TwoDLayer {
   public:
     /**
      * @brief Construct a new Conv 2d layer
@@ -102,6 +102,8 @@ class Conv2d : public WeightedLayer {
         return paddingSize;
     }
 
+    dim2d getOutputDims();
+
   private:
     // Inputs
     dim2d inputSize;