Merge pull request #16616 from alalek:dnn_fix_input_shape

* dnn: fix processing of input shapes

- importer: avoid using of .setInput() => .setInputShape()
- setInput: shape limitation check (partial)

* dnn(test): test .setInput() in readNet()

modules/core/src/matrix_wrap.cpp

@@ -569,6 +569,7 @@ int _InputArray::sizend(int* arrsz, int i) const
     }
     else
     {
+        CV_CheckLE(dims(i), 2, "Not supported");  // TODO Support EXPR with 3+ dims
         Size sz2d = size(i);
         d = 2;
         if(arrsz)