Python example to launch gzserver

[caguero]

🎉 New feature

Summary

It adds a higher level Python example using the GzServer action.

Test it

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.

[caguero]

Update (48feb03):

• Added another Python example to show how to launch the ros_gz bridge from Python using launch actions.
• Added a comment about launching the ROS component container with the bridge.