enable marking of sensors as "diagnostic"

[krbaker]

enable marking of sensors as "diagnostic" via https://developers.home-assistant.io/blog/2021/10/26/config-entity/#entity-categories and select what should be marked

happy to take changes to which entities should/shouldn't be but I do what to try and work from principles.
So far:

1. What is the purpose in life for this device, that measurement is not diagnostic, most else is (and inverter produces power so its watts and lifetime watts are its primary measurement)
2. If there is a summary measurement leave that only, the components are diagnostic (I selected watts where possible and left volts/amps as diagnostics)
3. Temp/Humidity in these electronic systems are diagnostics
4. I did keep working as a non-diagnistic for all
5. Customer SOC seems like the primary measurement for batteries (system SOC is in diagnostics)