Fix fifo files hanging the project wide search (#16039)

Release Notes:

- Fixed the issue related to the project wide search being stuck when
project contains .fifo files
- Might potentially solve the following issue
https://github.com/zed-industries/zed/issues/7360

crates/collab/src/db/tables/worktree_entry.rs

@@ -21,6 +21,7 @@ pub struct Model {
     pub is_external: bool,
     pub is_deleted: bool,
     pub scan_id: i64,
+    pub is_fifo: bool,
 }
 
 #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]