project_search: Add ability to search only for opened files (#16580)

Any suggestion?

Release Notes:
  - add ability for project search only for opend files.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/collab_ui/src/chat_panel/message_editor.rs

@@ -31,6 +31,7 @@ static MENTIONS_SEARCH: LazyLock<SearchQuery> = LazyLock::new(|| {
         false,
         Default::default(),
         Default::default(),
+        None,
     )
     .unwrap()
 });