In preparation for adding Schnorr versions of `CheckSig`, `VerifySignature`, and
`ComputeEntry`, give them an ECDSA specific name.

-BEGIN VERIFY SCRIPT-
sed -i 's/CheckSig(/CheckECDSASignature(/g' $(git grep -l CheckSig ./src)
sed -i 's/VerifySignature(/VerifyECDSASignature(/g' $(git grep -l VerifySignature ./src)
sed -i 's/ComputeEntry(/ComputeEntryECDSA(/g' $(git grep -l ComputeEntry ./src)
-END VERIFY SCRIPT-

The old name is confusing, as it doesn't store a scriptPubKey, but the
actually executed script.

A BIP-341 signature message may commit to the scriptPubKeys and amounts
of all spent outputs (including other ones than the input being signed
for spends), so keep them available to signature hashing code.