Fix bug with join with duplicate obs indices

[melonora]

Closes #815

The current way the join works on main does not account for duplicate indices in table.obs.index. This leads to a problem when performing the join as the indices are used to subset the table.

The implemented fix here gets the indices of the masked elements and then does a boolean masking on the obs dataframe with the index reset. This retrieves the integer indices which can then be used for subsetting the table. The behaviour of matching rows stays unchanged with this change.

from pathlib import Path
import spatialdata as sd
import spatialdata_plot

visium_zarr_path = Path("C:/Users/w-mv/PycharmProjects/spatialdata-notebooks/notebooks/examples/visium_brain.zarr")
visium_sdata = sd.read_zarr(visium_zarr_path)
(
    visium_sdata.pl.render_images(elements="ST8059050_hires_image")
    .pl.render_shapes(elements="ST8059050", color="mt-Co3")
    .pl.show()
)

now gives:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.75%. Comparing base (54e7dd0) to head (4ca78e5).
Report is 42 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #822      +/-   ##
==========================================
+ Coverage   91.73%   91.75%   +0.01%     
==========================================
  Files          46       46              
  Lines        7128     7130       +2     
==========================================
+ Hits         6539     6542       +3     
+ Misses        589      588       -1     

Files with missing lines	Coverage Δ
src/spatialdata/_core/query/relational_query.py	90.78% <100.00%> (+0.26%)	⬆️

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[quentinblampey]

Thanks @melonora for the quick fix 😊

[LucaMarconato]

Thanks @melonora! I just added some more tests. In doing this I found a case in which left_exclusive fails, for a problem related to indices but not due to the bug that this PR addresses. I tracked this in a separate issue and we can now merge this PR.