In preparation for the potential Taproot soft fork, libconsensus should be updated to support verifying Taproot scripts.

There are two changes I see as necessary:

- Add a VERIFY_TAPROOT flag
- Change the API to support passing in spent outputs (bitcoinconsensus_verify_script_with_spent_outputs?)
tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG,
                                "BIP66 example 3, without DERSIG", 0
                               ).Num(0).ScriptError(SCRIPT_ERR_EVAL_FALSE));
    tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG,
                                "BIP66 example 3, with DERSIG", SCRIPT_VERIFY_DERSIG
                               ).Num(0).ScriptError(SCRIPT_ERR_EVAL_FALSE));
    tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG << OP_NOT,
                                "BIP66 example 4, without DERSIG", 0
                               ).Num(0));
    tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG << OP_NOT,
                                "BIP66 example 4, with DERSIG", SCRIPT_VERIFY_DERSIG
                               ).Num(0));
    tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG,
                                "BIP66 example 5, without DERSIG", 0
                               ).Num(1).ScriptError(SCRIPT_ERR_EVAL_FALSE));
    tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG,
                                "BIP66 example 5, with DERSIG", SCRIPT_VERIFY_DERSIG
                               ).Num(1).ScriptError(SCRIPT_ERR_SIG_DER));
    tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG << OP_NOT,
                                "BIP66 example 6, without DERSIG", 0
                               ).Num(1));
    tests.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1C) << OP_CHECKSIG << OP_NOT,
                                "BIP66 example 6, with DERSIG", SCRIPT_VERIFY_DERSIG
                               ).Num(1).ScriptError(SCRIPT_ERR_SIG_DER));
    tests.push_back(TestBuilder(CScript() << OP_2 << ToByteVector(keys.pubkey1C) << ToByteVector(keys.pubkey2C) << OP_2 << OP_CHECKMULTISIG,
                                "BIP66 example 7, without DERSIG", 0
                               ).Num(0).PushSig(keys.key1, SIGHASH_ALL, 33, 32).EditPush(1, "45022100", "440220").PushSig(keys.key2));
    tests.push_back(TestBuilder(CScript() << OP_2 << ToByteVector(keys.pubkey1C) << ToByteVector(keys.pubkey2C) << OP_2 << OP_CHECKMULTISIG,
                                "BIP66 example 7, with DERSIG", SCRIPT_VERIFY_DERSIG
                               ).Num(0).PushSig(keys.key1, SIGHASH_ALL, 33, 32).EditPush(1, "45022100", "440220").PushSig(keys.key2).ScriptError(SCRIPT_ERR_SIG_DER));