Tool to migrate data between SpatialData versions

Is your feature request related to a problem? Please describe.
When the specification of SpatialData is changed, existing datasets do not have these changes, and under circumstances may even become incompatible.

For the in-memory representation, the library's reader functions support reading older versions (in most cases). However, users may want to upgrade the on-disk data to the latest version. Another case is when something is not covered by backward-compatibility of readers, e.g. due to errors in the data (#655).

Describe the solution you'd like
As discussed earlier, we want a tool for migrating data, if more format changes occur in future. I open this new issue for tracking this, since #655 was too specific and is closed.

Describe alternatives you've considered

• Relying on backward-compatible readers, then using write to save in the latest format: Some cases may not be covered by readers.
• Adding a new "upgrade" function to the spatialdata library: Migration is not a frequent use case and would bloat the library, especially if supporting special cases (one-time issues, erronous data). Additionally, backward-compatibility of certain features can be easily deprecated in the library, while still preserving it in a separate tool.
• Separate spatialdata-migrate tool

Start by reviewing the migration requirements in this issue and the related case in #655. Compare the proposed separate spatialdata-migrate tool with relying on backward-compatible readers and write; done would mean a defined migration approach for upgrading on-disk SpatialData across specification versions, including unsupported or erroneous data cases.