Implement threaded consumers to handle long running consumption microprocesses

[jackleland]

The idea on this is to spawn a daemon thread upon consumption which calls connection.process_data_events() and therefore keeps the connection alive. This will allow for very short heartbeats.

Careful care needs to be taken to ensure this is killed appropriately when the connection dies.

[jackleland]

Implemented as of #90. Will close when merged into main.