Functionality for selecting a small annotated ROI from an SpatialData object

[yhtgrace]

Describe your changes

Added functionality for selecting a small annotated ROI from a full Xenium dataset, to support quick testing of segmentation methods.

• subset_sample.ipynb crops WTA_Preview_FFPE_Breast_Cancer_Aligned.zarr given a GeoJSON polygon via sdata.query.bounding_box, and writes the results to *_subset.zarr
• The original aligned H&E was stored improperly in the zarr object, and so there is a quick fix as well that uses the original alignment matrix to re-align the H&E for the crop
• check_subset_sample.ipynb provides a quick visual check with cell-class polygons layered on top of the DAPI and H&E

Checklist before requesting a review

• I have performed a self-review of my code

• Check the correct box. Does this PR contain:

  • Breaking changes
  • New functionality
  • Major changes
  • Minor changes
  • Bug fixes

• Proposed changes are described in the CHANGELOG.md

• CI Tests succeed and look good!