perf(stack): Optimize fetching all cards from a stack

- Don't fetch stack, if we already know it
- fetch all comments at the same time, instead of for each card

Signed-off-by: Carl Schwan <carl.schwan@nextclound.com>

lib/Service/StackService.php

@@ -82,7 +82,7 @@ class StackService {
 			return;
 		}
 
-		$stack->setCards($this->cardService->enrichCards($cards));
+		$stack->setCards($this->cardService->enrichCards($cards, $stack));
 	}
 
 	private function enrichStacksWithCards($stacks, $since = -1) {