Onionmasq wait for stop - debugging

based on https://gitlab.torproject.org/dgoulet/onionmasq/-/tree/stop-command?ref_type=heads

This merge requests improves some bits of the Java side in order to ensure there are no memory leaks leading to multiple arti instances held. It adds also more debugging statements in order to help tracing down why multiple arti instances are sending event updates to the Android side via the JNI.