Improve Support of OpenCOSMO-RS in OPI

[haneug]

Is your feature request related to a problem? Please describe.
Currently it is not easily possible to run OpenCOSMO-RS with OPI. Due to the following issues:

Input:

• COSMORS is not part of SolvationModel simple keywords
• solvent in the cosmors block has to be written to the orca file with quotation marks

Output:

• The output is written to two new json files which are always written by OpenCOSMO-RS, namely basename.json and basename_out.json. The latter contains the solvation free energy while the former contains additional information about the calculation. The first also is problematic with the gbw json file as this has the exact same name.
• The property json file is just empty.

Describe the solution you'd like
First we should just fix the input side and add a simple getter for the solvation free energy from basename_out.json as this is the most important quantity.

Describe alternatives you've considered
In the long term we should also read the basename.json file.

[haneug]

It turns out the basename.json file is the input for opencosmors and basename_out.json is the output. In the long run the content of _out will be part of the property file in ORCA