ssh remoting: Show the host's GitHub name in the titlebar when sharing an SSH project (#19844)

The name (GitHub name) of the host was not displayed when sharing an ssh
project.

Previously we assumed that the a collaborator is a host if the
`replica_id` of the collaborator was `0`,
but for ssh project the `replica_id` is actually `1`.

<img width="329" alt="Screenshot 2024-10-28 at 18 16 30"
src="https://github.com/user-attachments/assets/c0151e12-a96f-4f38-aec1-4ed5475a9eaf">


Co-Authored-by: Thorsten <thorsten@zed.dev>

Release Notes:

- N/A

---------

Co-authored-by: Thorsten <thorsten@zed.dev>

crates/client/src/user.rs

@@ -48,6 +48,7 @@ pub struct Collaborator {
     pub peer_id: proto::PeerId,
     pub replica_id: ReplicaId,
     pub user_id: UserId,
+    pub is_host: bool,
 }
 
 impl PartialOrd for User {
@@ -824,6 +825,7 @@ impl Collaborator {
             peer_id: message.peer_id.ok_or_else(|| anyhow!("invalid peer id"))?,
             replica_id: message.replica_id as ReplicaId,
             user_id: message.user_id as UserId,
+            is_host: message.is_host,
         })
     }
 }