MetaDataCache does not deserialize PhasorsourceIndex

[clackner-gpa]

The MeasurementRecord model has a phasorsourceindex property, that defaults to 0
But the MetadataCache._extract_measurements never assigns a value to it.

For magnitudes and currents the phasor property get's assigned using the SignalReference but it ignores phasorsourceindex which is why this still works.

This leads to 2 issues:

• If a Signalreference is updated it will ignore SourceIndex based mapping and just not find a phasor
• If we attach anything but a magnitude or phase to a Phasor it will not find it and there is no easy way to manually find it from the MetadataCache