External inputs are currently only supported for initial transaction creation functions. Extend `solving_data` arguments as necessary to support fee bumping wallet transactions with non-wallet inputs.

https://github.com/bitcoin/bitcoin/pull/17211#issuecomment-897653994
{
        LOCK(m_wallet->cs_wallet);
        CoinsList result;
        for (const auto& entry : ListCoins(*m_wallet)) {
            auto& group = result[entry.first];
            for (const auto& coin : entry.second) {
                group.emplace_back(coin.outpoint,
                    MakeWalletTxOut(*m_wallet, coin));
            }
        }
        return result;
    }
    std::vector<WalletTxOut> getCoins(const std::vector<COutPoint>& outputs) override
    {
        LOCK(m_wallet->cs_wallet);
        std::vector<WalletTxOut> result;
        result.reserve(outputs.size());
        for (const auto& output : outputs) {
            result.emplace_back();
            auto it = m_wallet->mapWallet.find(output.hash);
            if (it != m_wallet->mapWallet.end()) {
                int depth = m_wallet->GetTxDepthInMainChain(it->second);
                if (depth >= 0) {
                    result.back() = MakeWalletTxOut(*m_wallet, it->second, output.n, depth);
                }
            }
        }
        return result;
    }
    CAmount getRequiredFee(unsigned int tx_bytes) override { return GetRequiredFee(*m_wallet, tx_bytes); }