[WIP] virtcontainers state manager

[sameo]

Description of problem

In general, virtcontainers is very stateful and that's an issue by itself. We're storing and fetching all sort of states without even trying to gather them from running entities for example.
A stateless virtcontainers is certainly unrealistic but should be an asymptotic goal.

Getting close to that goal means we need a better and more organized way to load and store states, and to validate state transitions. In other words, we need a package handling state management for all virtcontainers components.

[gnawux]

I think this is related with the persistence issue (#874 ) by @WeiZhang555

[sameo]

I think this is related with the persistence issue (#874 ) by @WeiZhang555

Yes, it is. Thanks.