addmultisigaddress creates an address respecting the setting, being unable to generate a specific type of address without also adding it to the wallet seems wrong.

I suppose in the future `addresstype` may be refactored to be wallet-specific, which would leave this non-wallet rpc call without an argument. Perhaps there should just be an optional parameter to set it.
{
    if (type == OUTPUT_TYPE_STRING_LEGACY) {
        output_type = OutputType::LEGACY;
        return true;
    } else if (type == OUTPUT_TYPE_STRING_P2SH_SEGWIT) {
        output_type = OutputType::P2SH_SEGWIT;
        return true;
    } else if (type == OUTPUT_TYPE_STRING_BECH32) {
        output_type = OutputType::BECH32;
        return true;
    }
    return false;
}
const std::string& FormatOutputType(OutputType type)
{
    switch (type) {
    case OutputType::LEGACY: return OUTPUT_TYPE_STRING_LEGACY;
    case OutputType::P2SH_SEGWIT: return OUTPUT_TYPE_STRING_P2SH_SEGWIT;
    case OutputType::BECH32: return OUTPUT_TYPE_STRING_BECH32;
    default: assert(false);
    }
}
CTxDestination GetDestinationForKey(const CPubKey& key, OutputType type)