feat: add `publish` to the `useChannel` hook

[ttypic]

Using publish method you can send messages to the derived channels (channels with filter qualifier, without attaching to the channel or using other workarounds)

[VeskeR]

I got confused a bit initially by the term transient realtime publishing, but it seems like it's just the same old .publish method called on a realtime channel, and it is considered transient if we never call attach/subscribe methods on a channel. Correct?