Handle buffer diff base updates and file renames properly for SSH projects (#14989)

Release Notes:

- N/A

---------

Co-authored-by: Conrad <conrad@zed.dev>

crates/collab/src/tests/channel_guest_tests.rs

@@ -52,7 +52,7 @@ async fn test_channel_guests(
     assert!(project_b.read_with(cx_b, |project, _| project.is_read_only()));
     assert!(project_b
         .update(cx_b, |project, cx| {
-            let worktree_id = project.worktrees().next().unwrap().read(cx).id();
+            let worktree_id = project.worktrees(cx).next().unwrap().read(cx).id();
             project.create_entry((worktree_id, "b.txt"), false, cx)
         })
         .await