Eredin: Destroyer of Worlds leader card desync

[Rickvs64]

The "Eredin: Destroyer of Worlds" leader card (discard 2 cards from hand, draw 1 selected card from deck) is causing desyncs. It appears that both clients have different ideas about the remaining cards in the player's hand, which causes issues and desyncs in subsequent cards that are played.
Might have to do with this leader ability (and the Emhyr "Draw from opponent's graveyard" ability) relying on index instead of an entire card object or filename?

Example:

1. Have multiple "Arachas" in your hand.
2. Use leader card to discard at least one of the "Arachas".
3. Play the remaining "Arachas" card in your hand and let Muster ability do its thing.
4. Seems to at least cause client A and client B to calculate the resulting score differently.
5. A few turns later the game will hang and/or log an undefined card error.

[Rickvs64]

Seems to be fixed by changing gwent.js to use "card: resp.filename" for all action strings as parameter instead of index. Previously removeCardHand and addCardHand would send an index instead.
Then obviously the various calls in abilities.js like for the Eredin leader card and Emhyr leader card I changed to use filename instead of index and return the card object from carousel selection.
Also circumvented an issue with the "discard 2 cards" carousel not updating after discarding the first out of two cards by adding a delay, someone smarter than me could probably come up with a proper fix.
Finally also had an issue where state would desync between clients. I added manual addCard() and removeCard() calls to both resolved promise branches to fix the other client not properly updating the opponent's graveyard and deck, which would otherwise result in later issues with both clients tallying up points on the board differently.

eredin_destroyer: {
	description: "Discard 2 cards and draw 1 card of your choice from your deck.",
	activated: async (card) => {
		let hand = board.getRow(card, "hand", card.holder);
		let deck = board.getRow(card, "deck", card.holder);
		if (card.holder.controller instanceof ControllerOponent) {
			// Wait for the opponent to choose which cards to discard and which to get
			await new Promise((resolve) => {
				let flag = 0;
				const handleMessage = async (event) => {
					const data = JSON.parse(event.data);
					if (data.type === "removeCardHand") {
						// OLD: const card = hand.cards[data.index];
						const card = player_op.hand.cards.find(c => c.filename === data.card);
						
						player_op.hand.removeCard(card);
						player_op.grave.addCard(card);
						flag+=1;
					}
					if (data.type === "addCardHand") {
						// OLD: const drawnCard = player_op.deck.cards[data.index];
						const drawnCard = player_op.deck.cards.find(c => c.filename === data.card);
						
						player_op.deck.removeCard(drawnCard);
						player_op.hand.addCard(drawnCard);
						flag+=1;
					}

					if (flag === 3) {
						resolve(true);
					}
				}
				socket.addEventListener('message', handleMessage);
			});

			return;
		} else
			Carousel.curr.exit();
		await ui.queueCarousel(hand, 1, (c,i) => {
			let cardToDiscard = c.cards[i]
			board.toGrave(cardToDiscard, c);
			if (Carousel.curr) Carousel.curr.update();
			return cardToDiscard;
		}, () => true);
		// Wait a bit so the board/hand state updates visually.
		await new Promise(r => setTimeout(r, 500));
		// Now just do it again instead of instructing the previous ui.queueCarousel() call to require 2 cards.
		// Fixes an issue with the carousel not updating inbetween selecting card 1 and 2.
		await ui.queueCarousel(hand, 1, (c,i) => {
			let cardToDiscard = c.cards[i]
			board.toGrave(cardToDiscard, c);
			if (Carousel.curr) Carousel.curr.update();
			return cardToDiscard;
		}, () => true);
		// Wait a bit so the board/hand state updates visually.
		await new Promise(r => setTimeout(r, 500));
		// Now finally pick one card to draw from your deck, again returning the card object to ensure receiving client can look it up.
		await ui.queueCarousel(deck, 1, (c,i) => {
			let cardToDraw = c.cards[i];
			board.toHand(cardToDraw, deck);
			return cardToDraw;
		}, () => true, true);

	},
	weight: (card, ai) => {
		let cards = ai.discardOrder(card).splice(0,2).filter(c => c.basePower < 7);
		if (cards.length < 2)
			return 0;
		return cards[0].abilities.includes("muster") ? 50 : 25;
	}
},