Adds `DerivedMeasurements` which are designed to perform post processing on
a provided MeasurementCsv.
Currently only a `DerivedEnergyMeasurements` class has been added which
has 2 purposes:
- Calculate energy from power results if not present using recorded timestamps,
falling back to a provided sample rate
- Calculate cumulative energy and average power from a specified MeasurementCSV
file.
