Rethink isothermal/mineralization type tags
In order to realize non-isothermal models, type tags inherit from the non-isothermal type tag and one has to set the properties IsothermalIndices, IsothermalNumEq etc. The actual types/values are then determined by the non-isothermal type tag.
Alternatively, one could also directly set the non-isothermal types (e.g. EnergyIndices), because the current way neither saves code nor does it improve readability. Since mineralization models use a similar pattern, in non-isothermal mineralization models it is particularly difficult to see which type is set/used.
Also, we would get rid of all properties like IsothermalIndices, IsothermalVolumeVariables, ..., NonMineralizationVtkOutputFields, NonMineralizationVolumeVariables ...