feat: add uuid bytes

[rfyiamcool]

summary

add Bytes() for uuid object.

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[it512]

func (uuid UUID) StringBytes() []byte {
 	var buf [36]byte
 	encodeHex(buf[:], uuid)
 	return buf[:]
 }

func (uuid UUID) Bytes() []byte{
 	return uuid[:] 
}

这样实现是不是更好？ Is it better to implement it this way? @rfyiamcool @bormanp

[bormanp]

@it512 To get the bytes representation of a uuid you just have to say uuid[:] as you suggest, there is no reason for a function call. I believe the rationale behind Bytes() is to prevent the conversion from []byte -> string -> []byte. Do you have an alternate suggestion for the functions name? HexBytes?