Refactor session

[arshamalh]

In the previous version, we stored all the containers and images in the session, that made our lists stale and could cause inconsistency between the real list of images and the one we have, that was also complex and hard to understand what the list is actually used for and we had a mechanism for updating it, I changed the session in a way that we only need to store the current item for cases we need it (remove and rename), in these cases also we don't rely on session but we rely on callback query data attach to the buttons (we also double check we session, but the can be removed), for listing containers and images we call the docker daemon every time but that will not be expensive.

Other refactors are for styling, variable naming and some other little changes.

[arshamalh]

I'm still not satisfied with the way we implemented session, but we got closer.