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_SCRIPT_SIGN_H
#define BITCOIN_SCRIPT_SIGN_H
#include <attributes.h>
#include <coins.h>
#include <hash.h>
#include <pubkey.h>
#include <script/interpreter.h>
#include <script/keyorigin.h>
#include <script/standard.h>
class CKey;