MJCF to SDF: Added gravity, wind and magnetic field

[ahcorde]

Signed-off-by: ahcorde ahcorde@gmail.com

🎉 New feature

Summary

Added gravity, wind and magnetic field

Checklist

• 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]

Codecov Report

Merging #56 (a39bdc3) into main (d559811) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #56      +/-   ##
==========================================
+ Coverage   97.79%   97.83%   +0.03%     
==========================================
  Files          16       16              
  Lines         636      646      +10     
==========================================
+ Hits          622      632      +10     
  Misses         14       14              

Impacted Files	Coverage Δ
...f_to_sdformat/mjcf_to_sdformat/converters/world.py	97.22% <100.00%> (+1.06%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d559811...a39bdc3. Read the comment docs.