Script to get results from a ci.ros2.org coverage build through json and
calculate the covarage rate from all the listed entries corresponding to
unit testing.
$ ./get_coverage_ros2_pkg.py <jenkins_build_url> <ros2_package_name>
Example:
$ ./get_coverage_ros2_pkg.py https://ci.ros2.org/job/ci_linux_coverage/182 rclcpp