MNT add new logos and themes for c4 plantuml

[MatthewSZhang]

Checklist

• Used a personal fork to propose changes
• A reference to a related issue: DOC update C4-PlantUML style and theme #222
• A description of the changes:

1. add new logos from local fork of gilbarbara-plantuml-sprites
2. Use new round style of C4 theme

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (7ed1b57) to head (4b25e3b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #227   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        10           
  Lines          859       859           
=========================================
  Hits           859       859           

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