segmentation_shape metadata reformat

[TeunHuijben]

connected to: funkelab/motile_tracker#459

Problem:

• tracksdata saves segmentation shape in geffmetadata as .extra.tracksdata.shape
• funtracks/motile_tracker save segmentation shape in zarr-metadata as segmentation_shape at the top level (outside the geff metadata)
• in retrospect, the latter is not the smartest design decision, because 1) top-level non-geff metadata doesn't survive round-trips, and 2) it is inconsistent with tracksdata

Solution:
This PR removes the segmentation_shape logic, and fully uses the existing tracksdata format of saving the shape in metadata.extra.tracksdata.shape. When reading the shape from the metadata we do a double check for backwards compatibility.

For geffs that are exported from motile_tracker and then imported, it doesn't matter where we save the shape, because that is an internal discussion. But for geffs exported by other tracksdata-based tracking tools (ultrack, hoct, etc.), we are now natively compatible.

I will implement the accompanying changes in motile_tracker in a separate PR there

[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.78%. Comparing base (38cfa7d) to head (daa236f).

Files with missing lines	Patch %	Lines
src/funtracks/import_export/geff/_import.py	84.61%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #260      +/-   ##
==========================================
- Coverage   93.78%   93.78%   -0.01%     
==========================================
  Files          59       59              
  Lines        3285     3282       -3     
==========================================
- Hits         3081     3078       -3     
  Misses        204      204              

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[cmalinmayor]

Can we add an API in tracksdata for saving and loading segmentation metadata (shape and voxel size?). Then, we don't need to depend on internal tracksdata implementation details, and tracksdata can change where this info is stored at any time.