Refactor to rumqttc

[jr1221]

Description

See how scylla does it, but basically switch out the paho_mqtt library with the rumqttc library. Benchmark CPU usage before and after switch.

Acceptance Criteria

• If CPU usage acceptable, switch to the rumqttc MQTT library.

Proposed Solution

Implement rumqttc library copying how Scylla does it. Ensure autoreconnect and reusbscribe work by canceling and starting mosquitto and confirming Calypso still works (we do not care about this test in simulation mode).

[marvin-g-personal]

1. EX: Only part of it can be tested on Mac. cargo run --bin simulate (test command) --> compile and run.