Add KilowattHourPerPound (kWh/lbs) to SpecificEnergy

[rutemja]

Is your feature request related to a problem? Please describe.
Our machines need to show the used energy per produced kilogram/pound. UnitsNet already supports the SI units in SpecificEnergy class, but the imperial units (like kWh/lbs) are missing.

Describe the solution you'd like
Please add kWh/lbs to SpecificEnergy class.

These should be the correct functions to calculate it from J/kg:

"FromUnitToBaseFunc": "{x} * 7.937e+6",
"FromBaseToUnitFunc": "{x} / 7.937e+6",

Thank you :)

[angularsen]

Hi, would you be interested in attempting a pull request? I'm happy to assist.
Same with #1091 .

https://github.com/angularsen/UnitsNet/wiki/Adding-a-New-Unit

[rutemja]

Done (my first PR 🥳)

[angularsen]

Great job!

Fixed in #1092 .