AscendC is an extended syntax for the C/C++ language that can be used to
write operators that run on Ascend NPU.
This commit introduce an operator(threshold) written in AscendC. Others
can refer to this to implement other operators.
AscendC can implement efficient fusion operators according to needs, in
this case, threshold execution speed increased by nearly 4 times.
Co-authored-by: CaoMengqing <cmq0113@163.com>