Support int8 and uint8 data types for Max and Min

[Honry]

I ran into an error with a Max node with int8 or uint8 data type: Could not find an implementation for Max(13) node with name '_0', then I find they are not registered in its kernel: https://github.com/microsoft/onnxruntime/blob/main/onnxruntime/core/providers/cpu/math/element_wise_ops.cc,
both Max and Min ops should support int8 and uint8 since opset 12.