Automatically re-assign services on server removal

When a server is removed from the cluster with `microceph cluster remove`, its roles should be re-assigned to other servers to avoid degrading the cluster.

This will most likely involved the removal hook and the leader then calling the services API on the new servers to have them bring up the needed services. Depends on #23

Start by reading the dependency in #23 and tracing the `microceph cluster remove` removal hook, the leader path, and the services API mentioned in the issue. Done means removing a server causes its roles to be reassigned to other servers and the needed services to be brought up without degrading the cluster.

Written by the indexing model from the issue text.