Add max precip ceiling

[dgergel]

This PR adds a maximum precipitation adjustment service so that maximum precipitation values above a threshold get adjusted to that threshold.

CLI interface is:

dodola adjust-maximum-precipitation /path/to/precip_to_correct.zarr \
--out /path/to/corrected_precip.zarr
-t 3000.0

This will then be added to the e2e precip downscaling workflow (no related issues to list at this time).

Note: this also updates the maximum validation precip threshold to 3000 mm (from its previous max of 2000mm).