Dump and expose WireGuard Go version info.

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

WireGuardNetworkExtension/WireGuardGoWrapper.h

@@ -16,4 +16,6 @@
 - (BOOL) turnOnWithInterfaceName: (NSString *)interfaceName settingsString: (NSString *)settingsString;
 - (void) turnOff;
 
++ (NSString *)versionWireGuardGo;
+
 @end

WireGuardNetworkExtension/WireGuardGoWrapper.m

@@ -44,6 +44,7 @@ static void do_log(int level, const char *tag, const char *msg);
 
 - (BOOL) turnOnWithInterfaceName: (NSString *)interfaceName settingsString: (NSString *)settingsString
 {
+    os_log([WireGuardGoWrapper log], "WireGuard Go Version %{public}s", wgVersion());
 
     wgSetLogger(do_log);
 
@@ -61,6 +62,10 @@ static void do_log(int level, const char *tag, const char *msg);
     wgTurnOff(self.handle);
 }
 
++ (NSString *)versionWireGuardGo {
+    return [NSString stringWithUTF8String:wgVersion()];
+}
+
 + (os_log_t)log {
     static os_log_t subLog = nil;
     static dispatch_once_t onceToken;