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?)
{
        scriptError = err;
        return *this;
    }
    TestBuilder& Opcode(const opcodetype& _op)
    {
        DoPush();
        spendTx.vin[0].scriptSig << _op;
        return *this;
    }
    TestBuilder& Num(int num)
    {
        DoPush();
        spendTx.vin[0].scriptSig << num;
        return *this;
    }
    TestBuilder& Push(const std::string& hex)