Enable H5Scombine to be used with special selections

It would be convenient if H5Scombine_select can be used with certain special selections: e.g. H5S_SEL_NONE and H5S_SEL_ALL.

Note that the intersection of two hyperslabs might not be considered a hyperslab selection. For example when using H5S_SELECT_AND with two non-overlapping selections (the result is H5S_SEL_NONE). We’re wondering if there’s a more rebust way of combining two selections than H5Scombine_select? Even a partial solution that works only for all combination of H5S_SEL_{NONE,HYPERSLAB,ALL} and all combination of H5S_SEL_{NONE,POINT,ALL} would be very helpful.

See: https://forum.hdfgroup.org/t/h5scombine-select-with-non-hyperslab-selections/12556