LibCards+Games: Return ErrorOr from deck-creation factory functions :^)

Also, be smarter about appending cards to the deck: we can
unchecked_append them to the deck, since we already ensured enough
capacity earlier.

Userland/Games/Spider/Game.cpp

@@ -74,7 +74,7 @@ void Game::setup(Mode mode)
         break;
     }
 
-    m_new_deck = Cards::create_deck(0, 0, heart_suits, spade_suits, Cards::Shuffle::Yes);
+    m_new_deck = Cards::create_deck(0, 0, heart_suits, spade_suits, Cards::Shuffle::Yes).release_value_but_fixme_should_propagate_errors();
 
     clear_moving_cards();