[RT/Docu] add a reactive transport benchmark of co2 injection
In this MR, a OGS-6 reactive transport benchmark is added. The benchmark work is motivated by the CO2LPIE project (shortened as CL-experiment), which is an in-situ experiment that is being conducted at the Mont Terri rock laboratory. In the experiment, carbon dioxide (CO_2) is injected into the Opalinus Clay leading to changes in its hydraulic, mechanical and chemical properties. This benchmark presents a simple numerical simulation to show the chemical behavior changes duing the CO2 injection. The OGS-6 results are verified against the results computed by the software PHREEQC.
Changes in this MR:
- Project files for the benchmark are added.
- Documentation is added.
- CTest for the benchamrk is added in the correspondes Tests.cmake file.