channel projects (#8456)

Add plumbing for hosted projects. This will currently show them if they
exist
but provides no UX to create/rename/delete them.

Also changed the `ChannelId` type to not auto-cast to u64; this avoids
type
confusion if you have multiple id types.


Release Notes:

- N/A

crates/collab_ui/src/collab_panel/channel_modal.rs

@@ -1,7 +1,7 @@
-use channel::{ChannelId, ChannelMembership, ChannelStore};
+use channel::{ChannelMembership, ChannelStore};
 use client::{
     proto::{self, ChannelRole, ChannelVisibility},
-    User, UserId, UserStore,
+    ChannelId, User, UserId, UserStore,
 };
 use fuzzy::{match_strings, StringMatchCandidate};
 use gpui::{