Assigning values to label coordinates when copying from existing values in add_years, add_regions, add_items

[jucordero]

Currently, when adding new years, regions or items to a dataarray or dataset, the non-dimension coordinates are not set or copied from the template set by "copy_from". This typically means these values have to be set manually after, which adds a few lines of code.

da = da.fbs.add_items("apples", copy_from="beef")
da["item_type"].loc[{"Item":"apples"}] = "fruit"
da["item_origin"].loc[{"Item":"apples"}] = "plant"

To avoid having to set these manually every time, it would be nice to have the option to pass a dictionary with the new values for selected non-dimension coordinates

coord_dict = {"item_type":"fruit", "item_origin":"plant"}
da = da.fbs.add_items("apples", copy_from="beef", coords=coord_dict)

This would be specially useful with label coordinates including names and / or numerical IDs