pubsub don't support channel prefix

[OuYangJinTing]

When using actioncable, can separate environment through the channel_prefix, but it doesn't seem to work with pubsub.

[palkan]

Yeah, we do not support the channel_prefix option right now. I think, it's worth adding.

[palkan]

Hey @OuYangJinTing,

A quick update: adding channel prefix support turned out to be not as simple as I thought in the first place (we should add it first at the anycable-rb level and then integrate into Rails SDK) but it's on my list of med-to-high priority things to do.