chr 27 implement pubsub

[christoff-linde]

This reworks the existing (now legacy) HTTP paradigm to use MQTT to publish to a rabbitMQ broker.

• feat(platformio.ini): add PubSubClient dependency
• refactor(main.cpp): replace old HTTP code with pubsub mqtt logic
• feat(main.cpp): add DHT sensor data recording

[linear[bot]]

CHR-27 Implement pub/sub