Exploring datasets with explicit relative mag paths is broken #8811
Description
When adding a remote dataset that has a datasource-properties.json we need to make sure that relative paths are processed correctly.
E.g. if a mag has a path ./color/1 this is currently just imported as is, but should be resolved relative to the location of the datasource-properties.json
Also, when serving the json for the wk-based zarr streaming we need to make sure usable paths are served, independent of where the data is actually stored.
- For on-disk layers
- For annotation layers
Related: #8762