Add configuration for Terminator chemistry

[mattldawson]

Terminator chemistry is a simple mechanism that will be used to demonstrate MICM and TUV-x usage in the MUSICA library. The mechanisms is described here: https://github.com/ESCOMP/CAM/blob/ab476f9b7345cbefdc4cf67ff17f0fe85d8c7387/src/chemistry/pp_terminator/chem_mech.doc#L1-L41

Blocked until MICM and TUV-x are fully functional in the MUSICA library

Acceptance Criteria

• A MICM configuration for the Terminator mechanism based on the CAM-Chem implementation is created for use in tests (https://github.com/ESCOMP/CAM/blob/ab476f9b7345cbefdc4cf67ff17f0fe85d8c7387/src/chemistry/pp_terminator/chem_mech.doc#L1-L41)
• A TUV-x configuration for the Terminator mechanism based on the CAM-Chem implementation is created for use in tests https://github.com/ESCOMP/CAM/blob/ab476f9b7345cbefdc4cf67ff17f0fe85d8c7387/src/chemistry/pp_terminator/chemistry.F90#L54-L55
  https://github.com/ESCOMP/CAM/blob/ab476f9b7345cbefdc4cf67ff17f0fe85d8c7387/src/chemistry/pp_terminator/chemistry.F90#L257-L261
• A test of the Terminator mechanism using the Backward Euler solver is included in the test suite

Ideas

• It might make sense to use a rate constant parameterization that is actually based on the radiation field to demonstrate TUV-x capabilities, but this will not exactly match the CAM-Chem results