Update material_color to use Entity.

[bperseghetti]

🦟 Bug fix

Summary

Use preferred method of Entity instead of name and parent_name

Checklist

• [x] Signed all commits for DCO
• [x] Added tests
• [x] Updated documentation (as needed)
• [x] Updated migration guide (as needed)
• [x] Consider updating Python bindings (if the library has them)
• [x] codecheck passed (See contributing)
• [x] All tests passed (See test coverage)
• [x] While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (ce3ccb9) 97.67% compared to head (65c8985) 97.67%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## gz-msgs10 #415 +/- ## ========================================== Coverage 97.67% 97.67% ========================================== Files 27 27 Lines 1163 1163 ========================================== Hits 1136 1136 Misses 27 27 ```

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