Add entity wrench map message

[srmainwaring]

🎉 New feature

Supersedes #200

Summary

Add map version of the existing entity_wrench message. Required for downstream gz-sim force visualization PR https://github.com/gazebosim/gz-sim/pull/1898.

Test it

Checklist

• [x] Signed all commits for DCO
• [ ] Added tests
• [ ] Added example and/or tutorial
• [ ] Updated documentation (as needed)
• [ ] Updated migration guide (as needed)
• [ ] Consider updating Python bindings (if the library has them)
• [ ] codecheck passed (See contributing)
• [ ] All tests passed (See test coverage)
• [ ] 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

Merging #328 (76acd1c) into gz-msgs9 (6844ef3) will not change coverage. The diff coverage is n/a.

:exclamation: Current head 76acd1c differs from pull request most recent head 2881808. Consider uploading reports for the commit 2881808 to get more accurate results

@@            Coverage Diff            @@
##           gz-msgs9     #328   +/-   ##
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  Coverage     95.41%   95.41%           
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  Files            10       10           
  Lines          1026     1026           
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  Hits            979      979           
  Misses           47       47           

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