Upload DSD tutorial material data to artifacts

[JoerivanEngelen]

For the 1.0-beta release, we need the tutorial material online.
The input dataset for iMOD Python needs to be available somehow.

Refinement

• Upload tutorial data to imod-artifacts
• Add pooch function to imod.data namespace.

Requirements

@FransRoelofsen asked if it could download the iMOD5 data to a user specified directory, instead of opening it immediately with the appropriate file opening function. Users have to do that themselves to get accustomed to opening data.