Add optional extra entities for metered envoy.

[mnederlof]

Also, use new endpoint (https://envoy.local/ivp/meters/reports/production) for fetching production and lifetime production and all optional entities

Extra entities:

• Ampere per phase
• Apparent power per phase
• Power factor per phase
• Reactive power per phase
• Frequency per phase

[mnederlof]

This is the reason why it is optional (and you need to enable it specifically):

Not really sure how useful they are, because without load on it, it will read 1Amp of power, because of the reactive power.

In combination of the power factor, i think we could also generate a metric with actual ampere load, but that could be a template thing too, as we're only exposing metrics generated by the envoy thus far.

We also might want to reconsider renaming the Current Voltage and Current Amps to RMS Voltage and RMS Ampere respectively, as that is the name of the value in the power production report.

[mnederlof]

The values from the phase are also provided by the realtime endpoint, so they will be updated more frequently, if realtime is enabled.