List command

[rizken]

As a user, I want to be able to view my credentials, so that I easily can get an overview over my added credentials.

Acceptance Criteria

• it should add a command named "list"
• it should list all credentials when running ttb list in the terminal

[bjornet]

@rizken what is it really that we want to show when we list? Is it the same info you see when you run ttb use or is it the token and everything?