Add exemplar launch test targeting Dashing - velodyne_node
Summary
This PR add a basic launch test to the velodyne_node
package. The launch test will serve as an exemplar for all packages yet to have launch tests added.
Some discussion points:
- Time delay before shutdown could probably be shorter given that we are just trying to bring up and then shutdown the node.
- The exit code in this example was -15 - not sure if there is a better way of shutting down the test.
Once this PR gets approved then I will update existing tests to follow this new template.