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
#ifndef BITCOIN_WALLET_FEEBUMPER_H
#define BITCOIN_WALLET_FEEBUMPER_H
#include <primitives/transaction.h>
class uint256;
enum class FeeEstimateMode;
struct bilingual_str;
namespace wallet {
class CCoinControl;