MQTT discovery: implement new attributes (state_class, last_reset, ...)

Feature Requests
1

A bunch of important attributes has been added, lately, related to long-term statistics and energy, but it seems MQTT discovery was not updated to support those.

This to request adding at least state_class and last_reset to the list of supported attributes in MQTT discovery.

2

Lack of documentation ? Zigbee2MQTT sends them since 1.21

homeassistant/sensor/0x04cf8cdf3c77ea45/energy/config

{"availability":[{"topic":"zigbee2mqtt/bridge/state"}],"device":{"identifiers":["zigbee2mqtt_0x04cf8cdf3c77ea45"],"manufacturer":"Xiaomi","model":"Mi power plug ZigBee EU (ZNCZ04LM)","name":"mi_outlet","sw_version":"Zigbee2MQTT 1.21.0"},"device_class":"energy","json_attributes_topic":"zigbee2mqtt/mi_outlet","last_reset_topic":"zigbee2mqtt/mi_outlet","last_reset_value_template":"1970-01-01T00:00:00+00:00","name":"mi_outlet_energy","state_class":"measurement","state_topic":"zigbee2mqtt/mi_outlet","unique_id":"0x04cf8cdf3c77ea45_energy_zigbee2mqtt","unit_of_measurement":"kWh","value_template":"{{ value_json.energy }}"}
3

Likely indeed.
I didn’t saw them in the abbreviations, so I assumed they were not yet supported, but the abbreviations are in the code itself