Add preprocessing and integration test for transformation coordinate

Add preprocessing and integration test for transformation coordinate

We have general checks for preprocessing in readir.cpp. This ensures that all relevant mdp options are validated properly.
The mathematical expression, however, is evaluated in the grompp integration test.
Then we have the mdrun integration test, which is based on the existing pull test for
a 3D umbrealla potential. Basically, we use the exact same setup and expect the same output, but apply the force on a transformation coordinate instead of a regular coordinate, only with a slightly lower numerical accuracy.