Register MeshInertialCalculator when loading sim from an SDF string

[iche033]

🎉 New feature

Summary

MeshInertialCalculator was added in #2061. It was only set for sim loaded from SDF file. This PR turns it on for sim loaded from SDF string.

Note this PR is targeted at gz-sim8 because it looks like there are a lot of changes between gz-sim8 and gz-sim9 due to #2638. After this is merged, we should merge gz-sim8 forward to gz-sim9

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.

[iche033]

@azeey - just want to double check with you if there's any reason that MeshInertialCalculator was only enabled for sim loaded from an SDF file and not SDF string.

[azeey]

It's probably an oversight. Looking at the code, it looks like there's some code duplication that led to it. I'd recommend moving the creation of sdfParserConfig out of the case statement so that the two branches can share the same sdfParserConfig object.