Handling undefined labels at the annotation statistics

[jihyeonyi]

Summary

Regarding the issue #1204 , modify compute_ann_statistics function to handle undefined labels.
And add corresponding unit test.

How to test

Checklist

• I have added unit tests to cover my changes.​
• I have added integration tests to cover my changes.​
• I have added the description of my changes into CHANGELOG.​
• I have updated the documentation accordingly

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below).

# Copyright (C) 2023 Intel Corporation
#
# SPDX-License-Identifier: MIT

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (cce5fc9) 80.48% compared to head (34f75ad) 80.48%.

❗ Current head 34f75ad differs from pull request most recent head 54833cc. Consider uploading reports for the commit 54833cc to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1232   +/-   ##
========================================
  Coverage    80.48%   80.48%           
========================================
  Files          269      269           
  Lines        29985    29993    +8     
  Branches      5856     5857    +1     
========================================
+ Hits         24133    24140    +7     
  Misses        4489     4489           
- Partials      1363     1364    +1     

Flag	Coverage Δ
macos-11_Python-3.8	79.13% <100.00%> (+<0.01%)	⬆️
ubuntu-20.04_Python-3.8	80.46% <100.00%> (+<0.01%)	⬆️
windows-2022_Python-3.8	80.45% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

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

[vinnamkim]

LGTM.