Elkoep-mqtt

ELANRF devices are all testable through the tool.

Accessing the last_value state of DT21

As a result of parsing device values, DUMMY_VAL may be set, which causes ha_diff to fail.

Improve type hinting throughout the project.

In the case of __on_disconnect, where __try_connect wasn't set to False, __on_connect is triggered early, causing subscriptions to be queued. The discovery ends with no devices found.

Fix the new elanrf FW format for connected topics