Enable clippy::clone_on_copy (#8728)

This PR enables the
[`clippy::clone_on_copy`](https://rust-lang.github.io/rust-clippy/master/index.html#/clone_on_copy)
rule and fixes the outstanding violations.

Release Notes:

- N/A

crates/editor/src/inlay_hint_cache.rs

@@ -2197,7 +2197,7 @@ pub mod tests {
             "another change #3",
         ] {
             expected_changes.push(async_later_change);
-            let task_editor = editor.clone();
+            let task_editor = editor;
             edits.push(cx.spawn(|mut cx| async move {
                 task_editor
                     .update(&mut cx, |editor, cx| {