Revert pure-go network monitoring and add wgSetConfig

This reverts commit 99f0e457c34480f25582d7b4ed509404712c648c and adds a
function too.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

wireguard-go-bridge/wireguard.h

@@ -14,6 +14,7 @@ typedef void(*logger_fn_t)(int level, const char *msg);
 extern void wgSetLogger(logger_fn_t logger_fn);
 extern int wgTurnOn(gostring_t ifname, gostring_t settings, int32_t tun_fd);
 extern void wgTurnOff(int handle);
+extern void wgSetConfig(int handle, gostring_t settings);
 extern char *wgVersion();
 
 #endif