Setup environment for workers started with dask-ssh

It would be great if there was a way to inject code to be run on a remote machine with dask-ssh

Currently the following is run on the remote machine.

https://github.com/dask/distributed/blob/master/distributed/deploy/ssh.py#L215-L217

For setting up environments (e.g. `module load application && ...` OR `cd /tmp/path/to/worker/area/ && ...`), currently I have to manually change the `cmd` string. Are there thoughts on a better way to do this?