libevent seems to have invaded `libbitcoin_common` via `url.cpp`

`url.cpp` is used only from `test/fuzz/string.cpp` and `wallet/rpcwallet.cpp`

libevent should only be required for bitcoind, bitcoin-cli and (due only to the hack of passing wallet names) bitcoin-qt

{
public:
    const int ID_NETWORKINFO = 0;
    const int ID_BLOCKCHAININFO = 1;
    const int ID_WALLETINFO = 2;
    const int ID_BALANCES = 3;
    
    UniValue PrepareRequest(const std::string& method, const std::vector<std::string>& args) override
    {
        if (!args.empty()) {
            throw std::runtime_error("-getinfo takes no arguments");
        }
        UniValue result(UniValue::VARR);
        result.push_back(JSONRPCRequestObj("getnetworkinfo", NullUniValue, ID_NETWORKINFO));
        result.push_back(JSONRPCRequestObj("getblockchaininfo", NullUniValue, ID_BLOCKCHAININFO));
        result.push_back(JSONRPCRequestObj("getwalletinfo", NullUniValue, ID_WALLETINFO));
        result.push_back(JSONRPCRequestObj("getbalances", NullUniValue, ID_BALANCES));
        return result;
    }
    
    UniValue ProcessReply(const UniValue &batch_in) override
    {
        UniValue result(UniValue::VOBJ);
        std::vector<UniValue> batch = JSONRPCProcessBatchReply(batch_in, batch_in.size());
        
        
        if (!batch[ID_NETWORKINFO]["error"].isNull()) {