Add CHELSA-W5E5 as new default atmosphere.

[juseg]

This meta-issue lists changes needed to make CHELSA-W5E5 the (hypothetical) new default in hyoga.open.atmosphere().

Needed in a first release

• Add CHELSA-W5E5 atmospheric data source #86
• Add CHELSA-W5E5 tiled aggregation. #88
• Add CHELSA-W5E5 standard deviation. #89
• Add CHELSA-W5E5 elevation data. #93
• Fix CHELSA-W5E5 precipitation scaling #94
• Add CHELSA-ERA5 tiled climatologies. #96
• Add CHELSA-W5E5 yearlong concatenation. #99
• Add CHELSA-W5E5 tile compression. #101

Subsequent or optional

• Homogenize atmosphere dataset coordinates.
• Download aggregated CHELSA-W5E5 tiles.
• Download aggregated CHELSA-ERA5 tiles.
• Default to 'cw5e5' in hyoga.open.atmosphere().