yoda: warning cleanup sweep (dead code + clippy --fix) (squashed)

Squash of 4 yoda commits:
- 84437e21 yoda: libcosmic-yoda dead-code purge (14->0 warnings)
- 999db0a4 yoda: cosmic-theme cleanup (4->0 warnings) — workspace at 0 warnings total
- 4743bb8e yoda: cargo clippy --fix on libcosmic-yoda (115->33 warnings)
- 675f3b59 chore: reduce local stack warnings

src/widget/cards.rs

@@ -527,7 +527,7 @@ where
             let c_layout = layout.next().unwrap();
             let state = clear_all_state.unwrap();
             self.clear_all_button.as_widget_mut().update(
-                state, &event, c_layout, cursor, renderer, clipboard, shell, viewport,
+                state, event, c_layout, cursor, renderer, clipboard, shell, viewport,
             );
         }
 
@@ -537,7 +537,7 @@ where
 
         for ((inner, layout), c_state) in self.elements.iter_mut().zip(layout).zip(tree_children) {
             inner.as_widget_mut().update(
-                c_state, &event, layout, cursor, renderer, clipboard, shell, viewport,
+                c_state, event, layout, cursor, renderer, clipboard, shell, viewport,
             );
             if shell.is_event_captured() || fully_unexpanded {
                 break;