Add CumSum and Round for Opset 11 (#1705)
* Add CumSum and Round for Opset 11
* add back 1 test
* Add back one broken test
* Add back more broken tests
* activate cumsum, round, dynamicquantizelinear tests
* removed python backend tests
* re-comment out dynamicquantizelinear_* tests. ReduceMin(11) not implemented yet
* re-comment out dynamicquantizelinear_* tests. ReduceMin(11) not implemented yet
* comment out cumsum_1d_reverse_exclusive
* Remove few types for csum. Keep only float, int32, int64
* Added friendly error message
* Added double type to pass ONNX tests.
