Issue #1922 fix meteogridcopy dump

[JoerivanEngelen]

Fixes #1922

Description

This PR does the following:

• Resolve an issue where pathlib.Path objects were assigned to xarray Datasets, but these cannot be serialized. Therefore enforce these to string.
• Add sanity check: roundtrip storing and loading for metaswap packages.
• Provide names as ids to package sanity checks, to have more informative test naming
• Rename package_sanity files from mf6 module.

Checklist

• Links to correct issue
• Update changelog, if changes affect users
• PR title starts with Issue #nr, e.g. Issue #737
• Unit tests were added
• If feature added: Added/extended example
• If feature added: Added feature to API documentation
• If pixi.lock was changed: Ran pixi run generate-sbom and committed changes

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[ClaireDons]

Looks good!