Isolate remaining old-style commands

[mislav]

Isolated issue and other remaining commands to their own packages. This resulted in a major cleanup in the old command/root.go and context package. 🤘

Fixes #759

TODO:

• port over alias commands and we're done!

[vilmibm]

thank you so much for all this ;_;

[mislav]

@vilmibm I've also ported alias commands and expansion since you've last reviewed. Please take a look!

Note that additional auth commands are now to be added in pkg/cmd/auth/auth.go instead of to command/root.go

[vilmibm]

alias port looks great and i'm excited for the root reorganization