Internal helper function to generate a list of provinces, depending on whether harmonized or non-harmonized coding is used.
reg_list(harmonized = TRUE)A named vector, where values are province IDs and names are corresponding province labels.
Logical. If TRUE (default), use harmonized province codes.
If FALSE, use non-harmonized province codes.
If harmonized = TRUE, the function uses ref_label$provinceh_label.
If harmonized = FALSE, the function uses ref_label$province_label.