[Proposal] refactor(cmd/*): move commands into packages

[Wabri]

Not working due to recursive import with cmd_vm and cmd_image, I'll solve it if the proposal will be accepted.

[belgaied2]

Hey @Wabri, sorry for taking so much time to answer.
Without taking this as a refusal or anything, but I wonder if this is necessary. Some inspiration that I had when creating this CLI tool are Rancher CLI and clusterctl.
If you look at both, they do not put any single command into its own package, here and here.

I fear this can introduce some complexity. What do you think are the benefits of modularizing these?