[kubernetes] Add ability to customize worker/scheduler pod names

In dask-kubernetes, you can use the `kubernetes.worker_name` value to add each user's name to the worker pod names. Is that customization something that can be done in Dask-gateway? I haven't figured that out yet - if it's not possible, I think that would be a useful feature to add. Would be nice for more quickly filtering pods and diagnosing any issues a particular user may be having. Happy to work on that but wanted to check first and see that I wasn't just missing some existing functionality somewhere