Add confusion matrix tools analysis

[akmalulkhairin]

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Motivation

Please describe the motivation of this PR and the goal you want to achieve through this PR.

1. Add analysis tool to generate confusion matrix adapted from https://github.com/open-mmlab/mmdetection

Modification

Please briefly describe what modification is made in this PR.

BC-breaking (Optional)

Does the modification introduce changes that break the back-compatibility of the downstream repos?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

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Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. The documentation has been modified accordingly, like docstring or example tutorials.

[codecov-commenter]

Codecov Report

Merging #93 (d08f230) into dev (4e39a45) will increase coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev      #93      +/-   ##
==========================================
+ Coverage   28.67%   28.76%   +0.08%     
==========================================
  Files         102      102              
  Lines        6604     6571      -33     
  Branches      990      985       -5     
==========================================
- Hits         1894     1890       -4     
+ Misses       4646     4617      -29     
  Partials       64       64              

Flag	Coverage Δ
unittests	28.74% <ø> (+0.08%)	⬆️

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

Impacted Files	Coverage Δ
...oi_extractors/rotate_single_level_roi_extractor.py	23.80% <0.00%> (-0.79%)	⬇️
mmrotate/models/dense_heads/rotated_anchor_head.py	10.12% <0.00%> (-0.64%)	⬇️
mmrotate/datasets/dota.py	11.17% <0.00%> (ø)
mmrotate/apis/inference.py	0.00% <0.00%> (ø)
mmrotate/datasets/pipelines/loading.py	30.43% <0.00%> (ø)
...ate/models/dense_heads/kfiou_rotate_retina_head.py	30.00% <0.00%> (ø)
...e/models/dense_heads/rotated_retina_refine_head.py	25.00% <0.00%> (ø)
...els/dense_heads/kfiou_rotate_retina_refine_head.py	25.00% <0.00%> (ø)
mmrotate/models/dense_heads/rotated_retina_head.py	16.66% <0.00%> (+0.36%)	⬆️
mmrotate/models/detectors/s2anet.py	17.64% <0.00%> (+0.50%)	⬆️
... and 5 more

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[yangxue0827]

LGTM

[OpenMMLab-Assistant003]

Hi @akmalulkhairin！First of all, we want to express our gratitude for your significant PR in the MMRotate project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.

We would also like to invite you to join our Special Interest Group (SIG) private channel on Discord, where you can share your experiences, ideas, and build connections with like-minded peers. To join the SIG channel, simply message moderator— OpenMMLab on Discord or briefly share your open-source contributions in the #introductions channel and we will assist you. Look forward to seeing you there! Join us ：https://discord.gg/raweFPmdzG

If you are Chinese or have WeChat，welcome to join our community on WeChat. You can add our assistant ：openmmlabwx. Please add "mmsig + Github ID" as a remark when adding friends：）
Thank you again for your contribution❤ @akmalulkhairin