New XCFGSET command

[rueian]

Port the XCFGSET.json file from https://github.com/redis/redis/tree/unstable/src/commands to our commands.json and run go generate to generate new builders.

Ref: redis/redis#14680

[Jgprog117]

I can work on this. I'll port the XCFGSET.json command definition from redis/redis and run the code generation.

[rueian]

Hi @Jgprog117, how is it going? We now have another contributor who wants to do the follow-up.