feat: RGBA color support

[jacobrkerstetter]

Description

• added keep_alpha flag to mcolors.to_hex calls
• expanded set body color and set face color tests to include opacity added plotting tests to test plotting with opacity

Issue linked

Checklist

• I have tested my changes locally.
• I have added necessary documentation or updated existing documentation.
• I have followed the coding style guidelines of this project.
• I have added appropriate unit tests.
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved to the PR if any.
• I have assigned this PR to myself.
• I have added the minimum version decorator to any new backend method implemented.
• I have made sure that the title of my PR follows Conventional commits style (e.g. feat: extrude circle to cylinder)

[codecov]

Codecov Report

Attention: Patch coverage is 91.52542% with 5 lines in your changes missing coverage. Please review.

Project coverage is 90.91%. Comparing base (b6b5eda) to head (5d23e4e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ansys/geometry/core/designer/body.py	88.46%	3 Missing ⚠️
src/ansys/geometry/core/plotting/plotter.py	71.42%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1788   +/-   ##
=======================================
  Coverage   90.90%   90.91%           
=======================================
  Files          92       92           
  Lines        8422     8471   +49     
=======================================
+ Hits         7656     7701   +45     
- Misses        766      770    +4     

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[RobPasMue]

One small extra comment - apart from that all good. Also, CI/CD seems to have some issues. Have you seen them? Once comment is implemented and CI/CD issues are solved I will approve the PR