This PR makes 2 relatively minor updates to the GW loss code.
It moves the list of additional reservoir-affected reaches (that aren't in the reach attributes file) out of the gw_utils.py and into the config file
It standardizes treatment of temps < 1 C in the annual stats calculations. Previously they were dropped in the calculations of the targets (to avoid freeze / thaw dynamics) and included in the calculations within the loss function (because the fft doesn't play nicely with missing values). Now temps < 1 are set to 1 in both locations. Setting the temps < 1 to 1 resulted in stats that more closely matched the results when they were removed than did leaving them in or setting temps < 0 to 0.
This PR makes 2 relatively minor updates to the GW loss code.