Fix package argument in manual search macro

[scpeters]

🦟 Bug fix

Fixes https://github.com/gazebosim/gz-common/issues/386 and typo from https://github.com/gazebosim/gz-cmake/pull/255

Summary

The package argument to ign_manual_search / gz_manual_search is package in everywhere except two places where it is PACKAGE_NAME. I believe this typo is the cause of https://github.com/gazebosim/gz-common/issues/386 and am testing this fix in https://github.com/gazebosim/gz-common/pull/387

Checklist

• [X] Signed all commits for DCO
• [ ] Added tests
• [ ] 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)
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