Install ign command

[chapulina]

Signed-off-by: Louise Poubel louise@openrobotics.org

🦟 Bug fix

Fixes https://github.com/ignitionrobotics/ign-gazebo/issues/886

Summary

It was removed by mistake on #55

Checklist

• [x] Signed all commits for DCO
• [ ] Added tests
• [ ] Updated documentation (as needed)
• [ ] Updated migration guide (as needed)
• [ ] codecheck passed (See contributing)
• [ ] All tests passed (See test coverage)
• [x] 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

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[j-rivero]

ouch, thanks @chapulina !