[FEAT] Add min and max values to output metadata

[Ionospheres]

Is your feature request related to a problem? Please describe.
It would be nice if the metadata contained the min and max values for any given output variable.

Describe the solution you'd like
I would like the min and max values of the output data to be calculated and included in the respective metadata.

Describe alternatives you've considered
An alternative is to not include the min and max value.

Additional context
Code seed from output_netcdf.cpp, ln 181:

int min = std::min_element(neutrals.species[iSpecies].density_scgc.begin(), neutrals.species[iSpecies].density_scgc.end());
denVar[iSpecies].putAtt(MIN_VAL, std::min_element(neutrals.species[iSpecies].density_scgc.begin(), neutrals.species[iSpecies].density_scgc.end()));