Remove major version from package name

[scpeters]

🎉 New feature

Part of gazebo-tooling/release-tools#1244.

Summary

This removes the major version from the package name in the following places:

• cmake project name
• package.xml name

An additional change was needed to resolve a name collision between cmake targets. In Ionic, the core library target name is gz-launch8, and the executable implementing the gz launch command has a target name of gz-launch. Removing the major version from the cmake project changes the core library target name to gz-launch, causing a name collision. To resolve this, the executable target name is changed, while setting its OUTPUT_NAME property to gz-launch to retain the same output file name.

Test it

• Check CI results

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.

[scpeters]

windows build is unhappy since it doesn't find gz-launch9 in the workspace; we would need to update our build scripts to handle package names without a major version, which shouldn't be too hard since we already have logic for supporting gz- and ignition- prefixes

• https://github.com/gazebo-tooling/release-tools/blob/c075a2fec566ba65f90a7b27f108caac84bfcef6/jenkins-scripts/lib/colcon-default-devel-windows.bat#L166-L176