* Message and bridge for MaterialColor.
This allows bridging MaterialColor from ROS to GZ and is
important for allowing simulation users to create status lights.
➡️ Forward port
Single feature forward port from modified cherry-pick
Note to maintainers: Remember to Merge with commit (not squash-merge or rebase)
* [#568 Add option to change material color from ROS. (backport #521)](https://github.com/gazebosim/ros_gz/pull/568) has been created for branch `jazzy`
Forward port of PR #486 from humble to iron
➡️ Forward port
Single feature forward port from modified cherry-pick
Note to maintainers: Remember to Merge with commit (not squash-merge or rebase)