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
class CTxOut;
class uint256;
enum
{
    SIGHASH_ALL = 1,
    SIGHASH_NONE = 2,
    SIGHASH_SINGLE = 3,
    SIGHASH_ANYONECANPAY = 0x80,
    SIGHASH_DEFAULT = 0, 
    SIGHASH_OUTPUT_MASK = 3,
    SIGHASH_INPUT_MASK = 0x80,
};
/** Script verification flags.
 *
 *  All flags are intended to be soft forks: the set of acceptable scripts under
 *  flags (A | B) is a subset of the acceptable scripts under flag (A).
 */
enum : uint32_t {
    SCRIPT_VERIFY_NONE      = 0,
    
    SCRIPT_VERIFY_P2SH      = (1U << 0),
    
    
    
    SCRIPT_VERIFY_STRICTENC = (1U << 1),
    
    SCRIPT_VERIFY_DERSIG    = (1U << 2),
    
    
    SCRIPT_VERIFY_LOW_S     = (1U << 3),