add ellipse to 'ShapesToBoxes' transform

[jihyeonyi]

Summary

Make 'ShapesToBoxes' transform support Ellipse.

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-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.03% ⚠️

Comparison is base (5f5ac2a) 80.00% compared to head (164311c) 79.97%.
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1121      +/-   ##
===========================================
- Coverage    80.00%   79.97%   -0.03%     
===========================================
  Files          258      258              
  Lines        29336    29147     -189     
  Branches      5746     5710      -36     
===========================================
- Hits         23469    23310     -159     
+ Misses        4517     4507      -10     
+ Partials      1350     1330      -20     

Flag	Coverage Δ
macos-11_Python-3.8	79.06% <ø> (-0.04%)	⬇️
ubuntu-20.04_Python-3.8	?
windows-2019_Python-3.8	79.88% <ø> (?)

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

Files Changed	Coverage Δ
src/datumaro/plugins/transforms.py	76.52% <ø> (ø)

... and 3 files with indirect coverage changes

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