Providers are too big

Provider are probably doing too many things now, it's difficult to read/change the code

The interface doesn't need to change if we don't see the need, we should at least split them internally

In particular, the vsphere provider contains logic that is not vsphere specific. If we were to add new providers, we would need to replicate this logic. We should move the logic elsewhere, where it can be shared

Start by locating the vSphere provider and mapping the logic it contains that is not vSphere-specific. Identify which parts could be shared by future providers; done means the provider-independent logic is separated without changing the public interface.

Written by the indexing model from the issue text.