Fix a bug getting processing options for SANS

- Replace functions that get options as strings with ones that return a dict for pre-processing and processing options (note that, for now, post-processing options are still always used as a string)
- Use a QMap in the C++ code so that SIP conversion works
- Update tests to use the QMap return type
- Convert from the QMap to a std::map where the results are used in the data processor so that subsequent code does not have to change

Re #21218