Standalone gz model executable

[sauk2]

🎉 New feature

Part of gazebosim/gz-tools#7

Summary

This PR introduces a standalone gz model executable, following a similar approach to gz-transport. The new executable is integrated into cmdmodel.rb.in, replacing its existing functionality.

The gz sim implementation remains unchanged in this PR and will be addressed in a subsequent update. Additionally, the command-line tests (gz_TEST.cc and ModelCommandAPI_TEST.cc) are now configured to build after the gz model executable is created.

Test it

Check for UNIT_gz_TEST and UNIT_ModelCommandAPI_TEST

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.

[sauk2]

@azeey The failure in the macOS job has been resolved!

[j-rivero]

An amazing work @sauk2 ! Minor comments and one important thing about the --pose parameter. Very close to get this ready.

[j-rivero]

It surprise me that we can remove this from the sources and the resulting code is still doing the same than before unless it was a superfluous source. Was it the case?

[sauk2]

This file is now used by the model_main.cc, so, CMakeLists.txt inside cmd now builds the executable using it.

./src/cmd/CMakeLists.txt

# Create model executable
set(model_executable gz-sim-model)
add_executable(${model_executable} model_main.cc ModelCommandAPI.cc)
target_link_libraries(${model_executable}
  gz-utils${GZ_UTILS_VER}::cli
  ${PROJECT_LIBRARY_TARGET_NAME}
)

[sauk2]

An amazing work @sauk2 ! Minor comments and one important thing about the --pose parameter. Very close to get this ready.

Thanks for the feedback! I have made the requested changes

[j-rivero]

The failing test seems like a flaky

and I think that we are good to go! Nice work again Saurabh.