Added vendor installation support for Jazzy and Rolling

[sauk2]

Closes #79

Summary

This PR introduces a check against the input list of ROS 2 distributions before installing Gazebo. In case of availability of packages as vendor installation, ros_gz is installed instead of Gazebo.

[sauk2]

Thanks for the feedback! I have made the changes you suggested.

[j-rivero]

Thanks for the feedback! I have made the changes you suggested.

Fantastic, we need to add a bit of documentation to the README file so people know that vendor packages are going to be installed starting with Jazzy. The pairings appear in https://gazebosim.org/docs/ionic/ros_installation/#gazebo-packages-for-ubuntu and the general description is at https://gazebosim.org/docs/ionic/ros2_gz_vendor_pkgs/

[sauk2]

Fantastic, we need to add a bit of documentation to the README file so people know that vendor packages are going to be installed starting with Jazzy. The pairings appear in https://gazebosim.org/docs/ionic/ros_installation/#gazebo-packages-for-ubuntu and the general description is at https://gazebosim.org/docs/ionic/ros2_gz_vendor_pkgs/

I have updated the documentation with that information

[j-rivero]

I have updated the documentation with that information

A added a bit more of info and an example so people can understand what is the option about. Good to go ! Great work !