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/src/db/queries/channels.rs

@@ -652,9 +652,14 @@ impl Database {
             .observed_channel_messages(&channel_ids, user_id, &*tx)
             .await?;
 
+        let hosted_projects = self
+            .get_hosted_projects(&channel_ids, &roles_by_channel_id, &*tx)
+            .await?;
+
         Ok(ChannelsForUser {
             channel_memberships,
             channels,
+            hosted_projects,
             channel_participants,
             latest_buffer_versions,
             latest_channel_messages,