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);
        std::set<WalletTx> result;
        for (const auto& entry : m_wallet->mapWallet) {
            result.emplace(MakeWalletTx(*m_wallet, entry.second));
        }
        return result;
    }
    bool tryGetTxStatus(const uint256& txid,
        interfaces::WalletTxStatus& tx_status,
        int& num_blocks,
        int64_t& block_time) override
    {
        TRY_LOCK(m_wallet->cs_wallet, locked_wallet);
        if (!locked_wallet) {
            return false;
        }
        auto mi = m_wallet->mapWallet.find(txid);
        if (mi == m_wallet->mapWallet.end()) {
            return false;
        }
        num_blocks = m_wallet->GetLastBlockHeight();
        block_time = -1;
        CHECK_NONFATAL(m_wallet->chain().findBlock(m_wallet->GetLastBlockHash(), FoundBlock().time(block_time)));
        tx_status = MakeWalletTxStatus(*m_wallet, mi->second);
        return true;
    }
    WalletTx getWalletTxDetails(const uint256& txid,