Add tests for transformations

[PythonFZ]

Thanks to @christophlohrmann most of the Transformations are now tested.

Still Missing tests / bad coverage

• [ ] integrated_heat_current
• [ ] kinaci_interaged_heat_current
• [ ] map_molecules
• [ ] momentum_flux
• [ ] thermal_flux

[christophlohrmann]

update: some of them/ the most common have one. The rest can be added at CI/unit_tests/transformations/test_transformations.py

[PythonFZ]

@christophlohrmann is this resolved?

[christophlohrmann]

no

[SamTov]

Waiting on some tests from @Fratorhe after he finishes the arguably less important PhD thesis work ;)