chore: Fix several style lints (#17488)

It's not comprehensive enough to start linting on `style` group, but
hey, it's a start.

Release Notes:

- N/A

crates/editor/src/persistence.rs

@@ -220,7 +220,6 @@ impl EditorDb {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use gpui;
 
     #[gpui::test]
     async fn test_save_and_get_serialized_editor() {