Although I understand the desire to use more human-friendly terms than
scriptPubKey, scriptSig, redeemScript, witness program, and witness, I
think it makes things less clear, particularly when we switch from
legacy to legacy P2SH to segwit v0 to segwit v1.
An additional problem is that, with scriptSig no longer being executed
(and witnesses never being executed), it's not quite accurate to use the
phrase "unlocking script".
This commit replaces "locking script" and "unlocking script" with either
the specific data type or with non-specific phrasing.