add tests for Sub

Author: rogday

testdata/dnn/onnx/data/input_sub_from_const1.npy

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+pytorch1.9:�

+;
1
+Constant_0"Constant* 
+value*

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+
+
1
+
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2Sub_1"Subtorch-jit-exportZ
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+

+
+b
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+B	

testdata/dnn/onnx/data/input_sub_from_const_broadcast.npy

@@ -0,0 +1,19 @@
+pytorch1.9:�

+�

1
+Constant_0"Constant*x
+value*l

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+
+
1
+
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2Sub_1"Subtorch-jit-exportZ
+
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+

+

+
+
+b
+
2
+

+

+
+
+B