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
if (m_wallet->IsLegacy()) return false;
        auto spk_man = m_wallet->GetScriptPubKeyMan(OutputType::BECH32M, false);
        return spk_man != nullptr;
    }
    OutputType getDefaultAddressType() override { return m_wallet->m_default_address_type; }
    CAmount getDefaultMaxTxFee() override { return m_wallet->m_default_max_tx_fee; }
    void remove() override
    {
        RemoveWallet(m_context, m_wallet, false );
    }
    bool isLegacy() override { return m_wallet->IsLegacy(); }
    std::unique_ptr<Handler> handleUnload(UnloadFn fn) override
    {
        return MakeHandler(m_wallet->NotifyUnload.connect(fn));
    }
    std::unique_ptr<Handler> handleShowProgress(ShowProgressFn fn) override
    {
        return MakeHandler(m_wallet->ShowProgress.connect(fn));
    }
    std::unique_ptr<Handler> handleStatusChanged(StatusChangedFn fn) override
    {
        return MakeHandler(m_wallet->NotifyStatusChanged.connect([fn](CWallet*) { fn(); }));
    }
    std::unique_ptr<Handler> handleAddressBookChanged(AddressBookChangedFn fn) override
    {
        return MakeHandler(m_wallet->NotifyAddressBookChanged.connect(
            [fn](const CTxDestination& address, const std::string& label, bool is_mine,
                 const std::string& purpose, ChangeType status) { fn(address, label, is_mine, purpose, status); }));
    }
    std::unique_ptr<Handler> handleTransactionChanged(TransactionChangedFn fn) override