feat: Implement blend_colors function for color blending

[TechyDaniel]

Description

Add a new function blend_colors in the meshops module to efficiently blend colors of vertices based on grouped indices. This function handles edge cases such as empty color arrays and index groups, and ensures that out-of-bound indices are properly managed. The implementation optimizes the blending process and adheres to project standards for error handling and input validation.

Type of change

Please delete options that are not relevant.

• [x ] New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.
Provide instructions so we can reproduce.
Please also list any relevant details for your test configuration.

• [x ] Test suite 1 - for functionality:
  # Case with simple groups and distinct colors
  # Case with a single group
  # Case with groups of 1 element
  # Case with empty colors array
  # Case with empty groups
• [x ] Test suite 2 - for IndexError

Test Configuration:

Checklist

• [x ] I confirm that the changes meet the user experience and goals outlined in the design plan (if there is one).
• [x ] My code follows the style guidelines of this project
• [ x] I have performed a self-review of my code
• [ x] I have commented my code, particularly in hard-to-understand areas
• [x ] I have made corresponding changes to the documentation
• I have updated any version info, if necessary.
• [x ] My changes generate no new warnings
• [ x] I have added tests that prove my fix is effective or that my feature works
• [x ] New and existing unit tests pass locally with my changes

Task: TECHART-325

[Olaf-Wolf3D]

I have some open questions, see comments.