Move power_range into the parameters for zh

[Jacfomg]

I think reading the power_level parameters for Zh from the parameters.json would be simpler for people calibrating as well as making qibo save at each report. This would follow what qm does. @hay-k could you have a look and maybe include this as part of your refactor ?

[hay-k]

This looks like pretty much independent from the refactor, so I would rather do it separately, not to clog the refactor PR too much.

[alecandido]

I agree with @hay-k, let's try to merge that PR as soon as possible.