Allow users to set the worker command in experimental.KubeCluster #537
Description
Currently, it isn't possible to set the worker command via the Python API, only via the YAML.
#475 covers allowing users to pass a full spec to KubeCluster, which is one route to solving this, but insisting users set the whole pod spec is definitely a nuclear option.
Exposing some common options as kwargs makes sense, but perhaps we should consider allowing folks to patch the spec too instead of having to supply the whole thing.