Fix metadata reshaping remaining issue

See merge request !180

Fix metadata reshaping when time dim is implicit and the split file dim array has time as a dimension

Develop reshape split metadata

See merge request !179

Change the class condition to is()

See merge request !178

Develop metadata reshape

See merge request !177

Finish metadata reshaping for retrieve = TRUE, including different combinations of merge_across_dims, merge_across_dims_narm, and split_multiselected_dims