New feature for channel hosts: warn and hide

- Send an in-app notification on Warpcast (not public, not push) to the the user directly them to your channel's norms

- We renamed Hide to Hide quietly for instances where you don't want to warn.

- Ban from channel remains unchanged

Reminder: this only applies to the channel feed, cast is unaffected at the protocol level. Currently a Warpcast-only feature but we will be moving the channel primitive we've been iterating on to the protocol later this year.

Because Farcaster accounts, the social graph and content live outside of a client (unlike a federated system), it's possible to use multiple clients at the same time (similar to being able to use multiple Ethereum wallets at the same time).

Is this censorship?

Every user has the freedom to post directly to a Hub at the protocol level with their own client or an open source client.

Clients, like Warpcast, are going to have their own moderation policies based on what they believe is the best UX for users. Warpcast also has to comply with US laws.