Clear memory states during bulk action if item is None

Prevents issues like https://forums.ankiweb.net/t/suggestion-copy-card-debug-info-button/54206/10 and #3634

rslib/src/scheduler/fsrs/memory_state.rs

@@ -85,7 +85,7 @@ impl Collection {
                 progress.update(true, |state| state.current_cards = idx as u32 + 1)?;
                 let mut card = self.storage.get_card(card_id)?.or_not_found(card_id)?;
                 let original = card.clone();
-                if let Some(req) = &req {
+                if let (Some(req), Some(item)) = (&req, item) {
                     card.set_memory_state(&fsrs, item, historical_retention.unwrap())?;
                     card.desired_retention = desired_retention;
                     // if rescheduling