allow calculation for custom constants

[michaldengusiak]

Describe the solution you'd like

sometimes to adjust calculations according to specific conditions requirements to adjust constants are needed..

allow modification to :
https://github.com/HoareLea/SAM_Mollier/blob/master/SAM_Mollier/SAM.Core.Mollier/Variables/Zero.cs

when we query these values via Inspect.mollierPoint or:

- SAMMollier.Psychrometrics
- SAMMollier.LoadByProcess where we can connect optional input ( _cp_ use current default but allow modification)
- SAMMollier.CalculateLoads

Additional context

https://ninova.itu.edu.tr/en/courses/faculty-of-aeronautics-and-astronautics/965/uck-421/ekkaynaklar?g96162

input could be node:
SAMMollier.SpecificHeat