TRM: Add a constitutive setting using the extended OGS-MFront interface

This MR...

• Generalizes some functionality of MaterialLib and ProcessLib/Deformation
• Adds a second constitutive setting SigSatEpsPT in addition to the Original one to the TRM process
• Adds a template parameter for the constitutive setting to the TRM process.

The constitutive settings SigSatEpsPT and Original are very similar. The new one, SigSatEpsPT, adds lots of code, but the differences to Original are not very large. This can be seen with your favourite diff tool, e.g.:
meld ProcessLib/ThermoRichardsMechanics/ConstitutiveSigSatEpsPT/ ProcessLib/ThermoRichardsMechanics/ConstitutiveOriginal/.
**I recommend that you take a look with a diff tool, before you make the MR review. It might save you a lot of work and brain capacity.**
I didn't find a good way reduce the copied boilerplate code, yet. Macros might work. Or some compile time template graph metaprogramming magic :-)

1. Feature description was added to the changelog
2. Tests covering your feature were added?
3. Any new feature or behavior change was documented?