Breaking API Changes

[tbnobody]

I will publish breaking changes in the Web API as well as in the MQTT topic structure here.
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[tbnobody]

Please see #1615 (comment)

tltr;

WebAPI endpoint /api/livedata/status and the websocket will change in future.
To get a overview list of all inverters just call /api/livedata/status and to get details for the inverter call /api/livedata/status?inv=<serial>

This reduces the memory consumption from 41kB to ~4kB at each call of the endpoint and makes space for new features.

[tbnobody]

Efficiency, YieldTotal, YieldDay and DC Power will be moved from the AC section to the INV section of the WebAPI (/api/livedata/status) as well as in the prometheus API (/api/prometheus/metrics). This is required because on inverters with more than one AC channel it's not possible to distinct between the outputs.

This is also in preparation of the new MQTT topics model.