pkg: add turtlebot3_gazebo

[ruben-arts]

Package required for simple nav2 examples

[traversaro]

I am not sure how the CI reaches the point of building the packages, as as far I can see the package is not released in Jazzy? See https://index.ros.org/p/turtlebot3_gazebo/#jazzy

[traversaro]

Indeed it seems that turtlebot3_gazebo is in the snapshot:

ros-jazzy/rosdistro_snapshot.yaml

Lines 5630 to 5633 in fd6ca4f

	turtlebot3_gazebo:
	tag: release/jazzy/turtlebot3_gazebo/2.2.5-5
	url: https://github.com/ros2-gbp/turtlebot3_simulations-release.git
	version: 2.2.5

and also in ros-distro https://github.com/ros/rosdistro/blob/99be012503026a70f3c107219d4fce8786ae2b4d/jazzy/distribution.yaml#L9362 . Perhaps it is automatically excluded by ROS index and/or the build farm as its dependency gazebo_ros_pkgs is not available (see https://github.com/ROBOTIS-GIT/turtlebot3_simulations/blob/646c42598f556066af6cf297641bf29182afc4c1/turtlebot3_gazebo/package.xml#L19)?

Anyhow, yes in ROS Jazzy there is no support for Gazebo Classic (see ros-simulation/gazebo_ros_pkgs#1532), so regardless of details I am not sure if it make sense to try to release this in ros-jazzy . @ruben-arts Can you clarify which nav2 examples you were targeting?