monero-wallet: decoy selection uniformity: reject torsioned outputs

[jeffro256]

In wallet2, after over-fetching potential decoy picks, we reject those for which Ko or Ca is torsioned: https://github.com/monero-project/monero/blob/893916ad091a92e765ce3241b94e706ad012b62a/src/wallet/wallet2.cpp#L9050-L9060.

If monero-wallet does not also emulate this behavior and includes a torsioned decoy in a broadcasted ring, then an external observer 1) can eliminate that decoy as the true spend and 2) determine that some wallet not built on wallet2 constructed this transaction.