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 <test/util/setup_common.h>
#include <banman.h>
#include <chainparams.h>
#include <consensus/consensus.h>
#include <consensus/params.h>
#include <consensus/validation.h>
#include <crypto/sha256.h>
#include <init.h>
#include <miner.h>
#include <net.h>
#include <net_processing.h>
#include <noui.h>
#include <pow.h>
#include <rpc/blockchain.h>
#include <rpc/register.h>
#include <rpc/server.h>
#include <script/sigcache.h>