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/check.cpp

@@ -171,6 +171,10 @@ void check_failed_auto(const Size_<int> v, const CheckContext& ctx)
 {
     check_failed_auto_< Size_<int> >(v, ctx);
 }
+void check_failed_auto(const std::string& v, const CheckContext& ctx)
+{
+    check_failed_auto_< std::string >(v, ctx);
+}
 
 
 }} // namespace