Line buffer editor (#5381)

* allow line editing

* cargo fmt

crates/nu-cli/src/repl.rs

@@ -161,6 +161,8 @@ pub fn evaluate_repl(
             }
         };
 
+        line_editor = line_editor.with_buffer_editor(config.buffer_editor.clone(), "nu".into());
+
         if config.sync_history_on_enter {
             if is_perf_true {
                 info!("sync history {}:{}:{}", file!(), line!(), column!());