ZIP 244: Reverse order of value and script_code in txin_sig_digest
ZIP 244: Reverse order of value and script_code in txin_sig_digest

This matches the order in which they are committed to in BIP 341 (and
also at the transaction level in S.2).

zcash/zips,zcash/zips,zcash/zips,zcash/zips