add a new internal hook to save ssh log (#15787)

* add a new internal hook to save ssh log

as title, when a ssh error ocure like #15785.
only when switch ``RUN_MODE`` to dev can we
found which error is ocure. But this way is
not a good idea for production envirment.

this changes try save ssh error mesage to the
log file like other log by a new internal hook.
I think it's usefull for find error message
in production envirment. Thanks.

Signed-off-by: a1012112796 <1012112796@qq.com>

* rename and fix nit

* Update modules/private/hook.go

Co-authored-by: silverwind <me@silverwind.io>

Co-authored-by: techknowlogick <matti@mdranta.net>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

cmd/serv.go

@@ -81,6 +81,10 @@ func fail(userMessage, logMessage string, args ...interface{}) {
 		}
 	}
 
+	if len(logMessage) > 0 {
+		_ = private.SSHLog(true, fmt.Sprintf(logMessage+": ", args...))
+	}
+
 	os.Exit(1)
 }