Add sample.region_centered_grid

[imagejan]

This samples close-by objects as contiguous regions, but centers on sparse objects that fit in a separate field of view.

In summary, we sample a common grid on each "cluster" of objects that are too close together to fit into separate fields of view.
This avoids any overlap larger than the specified overlap_ratio between tiles.

Closes #59.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.33%. Comparing base (0e3c635) to head (611ae1d).

❗ Current head 611ae1d differs from pull request most recent head 0e7f5c9. Consider uploading reports for the commit 0e7f5c9 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #60      +/-   ##
==========================================
- Coverage   98.43%   98.33%   -0.10%     
==========================================
  Files           9        9              
  Lines         320      361      +41     
  Branches       42       44       +2     
==========================================
+ Hits          315      355      +40     
  Misses          2        2              
- Partials        3        4       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.