Implement rejoining projects as guest when rejoining a room

Co-authored-by: Julia Risley <julia@zed.dev>

crates/collab/src/db/worktree_entry.rs

@@ -17,6 +17,8 @@ pub struct Model {
     pub mtime_nanos: i32,
     pub is_symlink: bool,
     pub is_ignored: bool,
+    pub is_deleted: bool,
+    pub scan_id: i64,
 }
 
 #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]