hide big team (feature request)

Currently there is possible to hide only the team where are no additional channels than the default _general_. Would propose allow to hide also big team where are more than default channel until there will be posting. Then those channels where are no posts, remain hidden and only relevant channels are visible. This will reduce the list of channels and allows to focus on those where something happens.

The issue names no files, tests, or entry points; begin by locating the client logic that controls team and channel visibility. Done means a team with multiple channels remains hidden until a channel has a post, while channels without posts stay hidden and relevant active channels become visible.

Written by the indexing model from the issue text.