Updating ruby script to use standalone executable

[sauk2]

🎉 New feature

Related to gazebosim/gz-tools#7

Summary

Updated the ruby script to use the standalone executable.

I also tried to resolve the issue of building the package because of the FrameSemantics class. You can check the error in ci of your branch.

I updated the CMakeLists and am not sure if the following is the right approach ...

  add_library(gz STATIC gz.cc ../FrameSemantics.cc)

Test it

Test any of the SDF commands

  gz sdf --help

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

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