The bias_calc was getting too large so let's break it in parts to make
is easier to maintain and navigate. Creating a new sub-module mixins.

The bias_calc was already quite large before adding PresRat. This commit
relocates QuantileDeltaMappingCorrection in a new sub-module that will
also receive PresRat.

Defining what to expose with wildcard.

Since UTF-8 has been the default in a while, it is not recommended
anymore using: '# -*- coding: utf-8 -*-'

To keep the following PR cleaner, this commit moves and combines a few
ruff setup from that PR into here.

style: Adding 'F' into ruff's checks

  It seems to be the only one conforming.

cfg: Missing to ignore F401

  Following @bnb32 setup.

style: Ignore F401 only on __init__

  Thanks to @ppinchuk 's tip! I missed that before.

Ignoring unused import in docs

Including Warning (W) rules

Using it as a bias' resource, and doesn't need to know how it is
organized internally.

Following the pattern, `local_qdm_bc` should be available as a bias
resource as well. I missed that when I was implementing it.