Some devices may not disconnect on engine stop

[qdot]

STR:

1. Start Engine
2. Connect 2 devices
3. Stop Engine

Expected:
Everything disconnects

Actual:
Sometimes only one device disconnects.

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There are a LOT of lifetime/destruction management issues in the library right now due to the copious amounts of Arc's used everywhere. Lots of circular references, lots of event loops not dying correctly, etc... This bug probably exists as a part of multiple layers from Buttplug through the Rust/Flutter bridge, but I'm filing it up top because it's probably the runtime management up here that's the main issue.