Add Metrics possibly required from the VDE to `metric_sample.proto`

[noah-kreutzer-frequenz]

The VDE guidelines specifiy all the metrics the DSO could ask for. This list of metrics needs to be checked and compared to the current state of metric_sample.proto. Afterwards it is open for discussion which values actually need to be part of the common, which can and should only be calculated right before sending out to the DSO.
Linked to this issue

[noah-kreutzer-frequenz]

Metrics to be calculated

• Active Power (in percent regarding the confirmed feed-in, supply power)
• Reactive Power (in percent regarding the confirmed –50 % Pinst)
• Gerneration unit Active Power (Value with sign -120% Pinst to 120% Pinst Resolution 1)
• Generation unit Reactive Power (Value with sign -50% Pinst to +50% Pinst Resolution 1)

Metrics that might be available

• Theoretically Available Power Output -> Calculation logic in Forecasting actor?
• Available under-excited reactive power -> limit Q from GridGuard
• Available over-excited reactive power -> limit Q from GridGuard

Error States switch states

• Connection point relay state
• Busbar disconnector
• Q-U Protection

Metrics that the DSO provides, that need to be sent back

• Setpoint of Grid Security Management P/Pinst
• Setpoint Specified Voltage UQ0/Uc
• Setpoint Reference Reactive Power Qref/Pb inst
• Setpoint Displacement Factor cos φ
• Setpoint Procedure for Static Voltage Control

[noah-kreutzer-frequenz]

In addition to that different binaries/ booleans need to be transmitted specifiying errors or activated switches. Would they be part of the metrics?
@tiyash-basu-frequenz