client: make list a subcommand of other commands

[xaur]

In some cases it feels like list command could be a subcommand of other command: /gc ls to list group chats, /ab ls to list address book, etc.

Just an UX idea.

[marcopeereboom]

While I like this idea not every list fits the mold (e.g. joins) and therefore it will break my OCD. I can be convinced to make this change but we need to identify what lists and make sure it isn't confusing.