feat(dnn): add checksum opr and test

GitOrigin-RevId: e784a76e0b

dnn/src/common/opr_trait.h

@@ -116,7 +116,7 @@ DEF(TQTBackward, 5, true, false);
 DEF(PowC, 2, false, true);
 DEF(UniformRNG, 1, true, true);
 DEF(GaussianRNG, 1, true, true);
-
+DEF(ChecksumForward, 1, true, false);
 }  // namespace megdnn
 
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