Provide helper methods on ZKSWallet to retrieve transaction receipts directly

[jpcenteno]

This pattern is repeating itself a lot in the codebase and usage examples:

        let tx_finalize_receipt = zk_wallet
            .get_eth_provider()
            .unwrap()
            .get_transaction_receipt(tx_finalize_hash)
            .await
            .unwrap()
            .unwrap();

We should provide the helper methods ZKSWallet.get_transaction_receipt_l1(hash) and ZKSWallet.get_transaction_receipt_l2(hash) for a simpler interface.