Add openrc support

[supasonix-zuv]

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[supasonix-zuv]

whoops, accidentally commented before I was done.
Anyway, it'd be cool if other OpenRC users could run this without having to write their own init file. I wrote up one, but I've never done it before, so IDK if it's any good.
amdgpu-fan.txt
I also wrote the config file, cause I think openrc wants it even if it doesn't have any settings, but IDK.
amdgpu-fanconf.txt