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

{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
            RPCHelpMan{"settxfee",
                "\nSet the transaction fee per kB for this wallet. Overrides the global -paytxfee command line parameter.\n",
                {
                    {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "The transaction fee in " + CURRENCY_UNIT + "/kB"},
                },
                RPCResult{
                    RPCResult::Type::BOOL, "", "Returns true if successful"
                },
                RPCExamples{
                    HelpExampleCli("settxfee", "0.00001")
            + HelpExampleRpc("settxfee", "0.00001")
                },
            }.Check(request);
    auto locked_chain = pwallet->chain().lock();
    LOCK(pwallet->cs_wallet);
    CAmount nAmount = AmountFromValue(request.params[0]);
    CFeeRate tx_fee_rate(nAmount, 1000);
    if (tx_fee_rate == CFeeRate(0)) {
        
    } else if (tx_fee_rate < pwallet->chain().relayMinFee()) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than min relay tx fee (%s)", pwallet->chain().relayMinFee().ToString()));
    } else if (tx_fee_rate < pwallet->m_min_fee) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than wallet min fee (%s)", pwallet->m_min_fee.ToString()));