implement channel management commands

[cblgh]

i want to manage which channels come up in listings, and invite people to them so that they don't miss out on its existence. cabal-client should implement functionality to make the following operations possible in the cli:

/hide <channel-name> which hides it when i list /channels, unless a flag is present e.g. /channels --all

/archive <channel-name> which hides it for everyone when they list /channel
a message could be printed in the channel:

cblgh has archived this channel. type /unarchive to restore

/invite <pubkey> <channel-name> where pubkey is the peer i want to invite to <channel-name>

• or /invite <nick> <channel-name> where every peer that currently has the name <nick> is invited
• multiple peers should be able to be invited at the same time too, and with autocomplete for nicks