Added support for generating logarithmic units

- "Logarithmic" and "LogarithmicScalingFactor" are used in the json file to indicate the unit is logarithmic.
- Added a separate PowerShell script to generate the logarithmic arithmetic operator source code.
Added support for generating arithmetic operator unit tests for logarithmic units
Merge branch 'feature/logarithmic-units' into feature/voltage-ratio
Added electric potential (voltage) ratio units.