Fix assorted linux issues (#10061)

- Fix a bug where modifiers would be dispatched before they changed
- Add a secondary modifier
- Improve keybindings

Release Notes:

- N/A

crates/project_panel/src/project_panel.rs

@@ -1456,7 +1456,7 @@ impl ProjectPanel {
                             if kind.is_dir() {
                                 this.toggle_expanded(entry_id, cx);
                             } else {
-                                if event.down.modifiers.command {
+                                if event.down.modifiers.secondary() {
                                     this.split_entry(entry_id, cx);
                                 } else {
                                     this.open_entry(entry_id, event.up.click_count > 1, cx);