fix(deisctl): "deisctl scale router=N" also starts units

This change fixes logic in `Destroy` to poll until `cAPI.UnitStates()` no longer contains the requested unit, and adds similar logic to `Create` to poll until the unit has a state. This allows both methods actually to be synchronous, which made chaining them together in `Scale` trivial.

The side effect is that `deisctl [un]install platform` is a bit slower, but now it is reporting actual states instead of planned ones.