Compute iou

[cmalinmayor]

Proposed Change

Add IOU computation to candidate graph creation. I tried doing the np.unique shortcut for IOU computation, but I had to tinker with it. Will check against a reference implementation before merging to see if it can be more efficient.

Checklist

Go through these things before merge. Actions should run automatically to test them, but for information on how to run locally, see CONTRIBUTING.md.

• [x] I have added tests that prove that my feature works in various situations or tests the bugfix (if applicable).
• [x] I have checked that the tests pass and I maintained or improved test coverage (if applicable).
• [x] I have written docstrings and checked that they render correctly in the documentation build.
• [x] I have checked that mypy type checking passes.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 97.14286% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 78.21%. Comparing base (b8b215f) to head (8e0616c).

Files	Patch %	Lines
...toolbox/candidate_graph/graph_from_segmentation.py	97.05%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #4 +/- ## ========================================== + Coverage 75.56% 78.21% +2.64% ========================================== Files 9 9 Lines 176 202 +26 ========================================== + Hits 133 158 +25 - Misses 43 44 +1 ```

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