CCDCesque: Use list of values for min_rmse

[valpasq]

We might expect different bands to vary in their RMSE due to differences in scaling. Therefore,
min_rmse hyperparameter for CCDCesque should accept either (a) a single value that will be applied to all bands (currently implemented) or (b) a list of values for each band, similar to how min_values/max_values for bands is currently structured.

[ceholden]

Implemented suggestion in last commit. Given an example of using 7 (no-mask) bands, parameterize as follows:

min_rmse: 100

or

min_rmse: [100, 100, 100, 100, 100, 100, 100]

Seems to work as using an array of 7 "100" values passes the same test as using min_rmse=100.