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

#include <qt/bitcoin.h>
#include <util/translation.h>
#include <QCoreApplication>
#include <functional>
#include <string>
extern const std::function<std::string(const char*)> G_TRANSLATION_FUN = [](const char* psz) {
    return QCoreApplication::translate("bitcoin-core", psz).toStdString();
};
int main(int argc, char* argv[]) { return GuiMain(argc, argv); }