Change decadal loading module for changed data paths

Hi @vagudets

@cdelgado and I open this issue to track the needed changes in the decadal loading module. Some datasets require only the modification of the directory path in archive, but the data structure of some dataset(s), like HadGEM3 tasmin/tasmax/tas, has changed from 10 fyears per one file to 1 fyear per file, so some parts in the loading module need to be changed, too.

Since the path will keep changing (from the record saying), we only want to make two datasets work well for now so we can do the multi-model development. But we can list all the changes we've detected here.

• HadGEM3 / monthly / tas
• HadGEM3 / daily/ tasmin, tasmax
• CMCC-CM2-SR5
• [ ]

@cdelgado feel free to edit the list above!

Best,
An-Chi